Makefile(s): avoid recipe prefix in conditional statements

In GNU Make commit 07fcee35 ([SV 64815] Recipe lines cannot contain
conditional statements, 2023-05-22) and following, conditional
statements may no longer be preceded by a tab character (which Make
refers to as the recipe prefix).

There are a handful of spots in our various Makefile(s) which will break
in a future release of Make containing 07fcee35. For instance, trying to
compile the pre-image of this patch with the tip of make.git results in
the following:

    $ make -v | head -1 && make
    GNU Make 4.4.90
    config.mak.uname:842: *** missing 'endif'.  Stop.

The kernel addressed this issue in 82175d1f9430 (kbuild: Replace tabs
with spaces when followed by conditionals, 2024-01-28). Address the
issues in Git's tree by applying the same strategy.

When a conditional word (ifeq, ifneq, ifdef, etc.) is preceded by one or
more tab characters, replace each tab character with 8 space characters
with the following:

    find . -type f -not -path './.git/*' -name Makefile -or -name '*.mak' |
      xargs perl -i -pe '
        s/(\t+)(ifn?eq|ifn?def|else|endif)/" " x (length($1) * 8) . $2/ge unless /\\$/
      '

The "unless /\\$/" removes any false-positives (like "\telse \"
appearing within a shell script as part of a recipe).

After doing so, Git compiles on newer versions of Make:

    $ make -v | head -1 && make
    GNU Make 4.4.90
    GIT_VERSION = 2.44.0.414.gfac1dc44ca9
    [...]

    $ echo $?
    0

[j6t: cherry-picked from 728b9ac]

Reported-by: Dario Gjorgjevski <[email protected]>
Signed-off-by: Taylor Blau <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>
Signed-off-by: Johannes Sixt <[email protected]>

Author: ttaylorr

Makefile

@@ -107,12 +107,12 @@ endif
 
 ifeq ($(uname_S),Darwin)
 	TKFRAMEWORK = /Library/Frameworks/Tk.framework/Resources/Wish.app
-	ifeq ($(shell echo "$(uname_R)" | awk -F. '{if ($$1 >= 9) print "y"}')_$(shell test -d $(TKFRAMEWORK) || echo n),y_n)
+        ifeq ($(shell echo "$(uname_R)" | awk -F. '{if ($$1 >= 9) print "y"}')_$(shell test -d $(TKFRAMEWORK) || echo n),y_n)
 		TKFRAMEWORK = /System/Library/Frameworks/Tk.framework/Resources/Wish.app
-		ifeq ($(shell test -d $(TKFRAMEWORK) || echo n),n)
+                ifeq ($(shell test -d $(TKFRAMEWORK) || echo n),n)
 			TKFRAMEWORK = /System/Library/Frameworks/Tk.framework/Resources/Wish\ Shell.app
-		endif
-	endif
+                endif
+        endif
 	TKEXECUTABLE = $(shell basename "$(TKFRAMEWORK)" .app)
 endif
 
@@ -143,9 +143,9 @@ ifeq ($(exedir),$(gg_libdir))
 endif
 gg_libdir_sed_in := $(gg_libdir)
 ifeq ($(uname_S),Darwin)
-	ifeq ($(shell test -d $(TKFRAMEWORK) && echo y),y)
+        ifeq ($(shell test -d $(TKFRAMEWORK) && echo y),y)
 		GITGUI_MACOSXAPP := YesPlease
-	endif
+        endif
 endif
 ifneq (,$(findstring MINGW,$(uname_S)))
 ifeq ($(shell expr "$(uname_R)" : '1\.'),2)
@@ -220,9 +220,9 @@ ifdef NO_MSGFMT
 	MSGFMT ?= $(TCL_PATH) po/po2msg.sh
 else
 	MSGFMT ?= msgfmt
-	ifneq ($(shell $(MSGFMT) --tcl -l C -d . /dev/null 2>/dev/null; echo $$?),0)
+        ifneq ($(shell $(MSGFMT) --tcl -l C -d . /dev/null 2>/dev/null; echo $$?),0)
 		MSGFMT := $(TCL_PATH) po/po2msg.sh
-	endif
+        endif
 endif
 
 msgsdir     = $(gg_libdir)/msgs