treewide: substitute pname for strings

Inspired by #387725 (comment), script is based on #336172 using what i learned in #386865, part of #346453

Should be zero rebuilds.

All candidates were made using:

```shell

export NIXPKGS_ALLOW_UNFREE=1
export NIXPKGS_ALLOW_INSECURE=1
export NIXPKGS_ALLOW_BROKEN=1

git-wait restore .

test -s packages.json || ( set -x;
  time nix-env --extra-experimental-features no-url-literals --option system x86_64-linux -f ./. -qaP --json --meta --drv-path --out-path --show-trace --no-allow-import-from-derivation --arg config '{ allowAliases = false; }' > packages.json
)

list_attrpath_fname_col() {
    jq <packages.json 'to_entries[] | select(.value.meta.position==null|not) | "\(.key)\t\(.value.meta.position)"' -r |
        sed -e "s#\t$(realpath .)/#\t#" |
        sed -e 's#:\([0-9]*\)$#\t\1#' |
        grep . |
        grep -iv haskell |
        grep -iv /top-level/ |
        grep -iv chicken |
        grep pkgs/by-name/ |
        grep -iv build |
        grep -E '/(package|default)\.nix'
}

FLOCKDIR="$(mktemp -d)"
N_WORKERS=4
while read attrpath fname col; do
    grep -qE 'repo *= *("\$\{pname\}"|pname);' "$fname" || continue

    echo | (
        # mutex on fname
        flock --nonblock 200 || {
            >&2 echo "failed to aquire lock for $fname"
            exit 1
        }

        echo "$attrpath"
        data="$(nix eval --impure  --expr 'with import ./. {}; { inherit ('"$attrpath"') pname drvPath passthru meta; drvPath2='"$attrpath"'.src.drvPath; }' --json)" || exit
        test -n "$data" || exit
        pname="$(jq <<<"$data" .pname -r)"
        test -n "$pname" || exit

        (set -x
            sd -F '${pname}'  "$pname"         "$fname"
            sd -F ' = pname;' " = \"$pname\";" "$fname"
        )

        data2="$(nix eval --impure  --expr 'with import ./. {}; { inherit ('"$attrpath"') pname drvPath passthru meta; drvPath2='"$attrpath"'.src.drvPath; }' --json)"
        if [[ "$data" = "$data2" ]]; then
            (set -x; git-wait add "$fname")
        else
            (set -x; git-wait restore "$fname")
            exit
        fi

        (set -x
            sd -F ' rec {' ' {' "$fname"
        )

        data3="$(nix eval --impure  --expr 'with import ./. {}; { inherit ('"$attrpath"') pname drvPath passthru meta; drvPath2='"$attrpath"'.src.drvPath; }' --json 2>/dev/nul)"

        if [[ "$data" = "$data3" ]]; then
            (set -x; git-wait add "$fname")
        else
            (set -x; git-wait restore "$fname")
        fi

    ) 200>"$FLOCKDIR"/"$(sha256sum - <<<"$fname" | cut -d' ' -f1)".lock &

    while [[ $(jobs -p | wc -l) -ge $N_WORKERS ]]; do
        wait -n < <(jobs -p) || true
    done

done < <(list_attrpath_fname_col)

wait

git restore .

time nix-env --extra-experimental-features no-url-literals --option system x86_64-linux -f ./. -qaP --json --meta --drv-path --out-path --show-trace --no-allow-import-from-derivation --arg config '{ allowAliases = false; }' > packages2.json
```

`diff packages{,2}.json` is empty, indicating that no package nor src derivation has changed.
I checked and cherry-picked the changes using `GIT_DIFF_OPTS='-u15' git -c interactive.singleKey=true add --patch`

Author: pbsds

pkgs/by-name/_0/_0verkill/package.nix

@@ -8,13 +8,13 @@
   libXpm,
 }:
 
-gccStdenv.mkDerivation rec {
+gccStdenv.mkDerivation {
   pname = "0verkill";
   version = "unstable-2011-01-13";
 
   src = fetchFromGitHub {
     owner = "hackndev";
-    repo = pname;
+    repo = "0verkill";
     rev = "522f11a3e40670bbf85e0fada285141448167968";
     sha256 = "WO7PN192HhcDl6iHIbVbH7MVMi1Tl2KyQbDa9DWRO6M=";
   };

pkgs/by-name/_3/_3proxy/package.nix

@@ -11,7 +11,7 @@ stdenv.mkDerivation rec {
 
   src = fetchFromGitHub {
     owner = "3proxy";
-    repo = pname;
+    repo = "3proxy";
     rev = version;
     sha256 = "sha256-4bLlQ/ULvpjs6fr19yBBln5mRRc+yj+zVLiTs1e/Ypc=";
   };

pkgs/by-name/_4/_4ti2/package.nix

@@ -12,8 +12,8 @@ stdenv.mkDerivation rec {
   version = "1.6.10";
 
   src = fetchFromGitHub {
-    owner = pname;
-    repo = pname;
+    owner = "4ti2";
+    repo = "4ti2";
     rev = "Release_${builtins.replaceStrings [ "." ] [ "_" ] version}";
     hash = "sha256-Rz8O1Tf81kzpTGPq7dkZJvv444F1/VqKu7VuRvH59kQ=";
   };

pkgs/by-name/_6/_6tunnel/package.nix

@@ -11,7 +11,7 @@ stdenv.mkDerivation rec {
 
   src = fetchFromGitHub {
     owner = "wojtekka";
-    repo = pname;
+    repo = "6tunnel";
     rev = version;
     sha256 = "0zsx9d6xz5w8zvrqsm8r625gpbqqhjzvjdzc3z8yix668yg8ff8h";
   };

pkgs/by-name/_9/_9menu/package.nix

@@ -9,13 +9,13 @@
   libXext,
 }:
 
-stdenv.mkDerivation rec {
+stdenv.mkDerivation {
   pname = "9menu";
   version = "unstable-2021-02-24";
 
   src = fetchFromGitHub {
     owner = "arnoldrobbins";
-    repo = pname;
+    repo = "9menu";
     rev = "00cbf99c48dc580ca28f81ed66c89a98b7a182c8";
     sha256 = "arca8Gbr4ytiCk43cifmNj7SUrDgn1XB26zAhZrVDs0=";
   };

pkgs/by-name/aa/aaa/package.nix

@@ -10,7 +10,7 @@ rustPlatform.buildRustPackage rec {
 
   src = fetchFromGitHub {
     owner = "DomesticMoth";
-    repo = pname;
+    repo = "aaa";
     rev = "v${version}";
     sha256 = "sha256-gIOlPjZOcmVLi9oOn4gBv6F+3Eq6t5b/3fKzoFqxclw=";
   };

pkgs/by-name/aa/aardvark-dns/package.nix

@@ -11,7 +11,7 @@ rustPlatform.buildRustPackage rec {
 
   src = fetchFromGitHub {
     owner = "containers";
-    repo = pname;
+    repo = "aardvark-dns";
     rev = "v${version}";
     hash = "sha256-mWaB1E/n/N2Tb5bqrMJX2XfPvZBCG+dxar3kGCHgv0I=";
   };

pkgs/by-name/aa/aaxtomp3/package.nix

@@ -23,7 +23,7 @@ resholve.mkDerivation rec {
 
   src = fetchFromGitHub {
     owner = "krumpetpirate";
-    repo = pname;
+    repo = "aaxtomp3";
     rev = "v${version}";
     hash = "sha256-7a9ZVvobWH/gPxa3cFiPL+vlu8h1Dxtcq0trm3HzlQg=";
   };

pkgs/by-name/ac/acsccid/package.nix

@@ -20,7 +20,7 @@ stdenv.mkDerivation rec {
 
   src = fetchFromGitHub {
     owner = "acshk";
-    repo = pname;
+    repo = "acsccid";
     rev = "v${version}";
     sha256 = "12aahrvsk21qgpjwcrr01s742ixs44nmjkvcvqyzhqb307x1rrn3";
   };

pkgs/by-name/ad/adbfs-rootless/package.nix

@@ -13,7 +13,7 @@ stdenv.mkDerivation rec {
 
   src = fetchFromGitHub {
     owner = "spion";
-    repo = pname;
+    repo = "adbfs-rootless";
     rev = "fd56381af4dc9ae2f09b904c295686871a46ed0f";
     sha256 = "atiVjRfqvhTlm8Q+3iTNNPQiNkLIaHDLg5HZDJvpl2Q=";
   };