Actually build gix to check MSRV

This changes `cargo check` commands to `cargo build` in the
`ci-check-msrv` recipe in the `justfile`, which the `check-msrv` CI
jobs in `msrv.yml` use. (It updates a CI step name accordingly.)

The idea is to make sure at least `gix`, with the two combinations
of features tested, actually *builds* under the MSRV toolchain.

As in f10f18d, this also updates the `Makefile` rule corresponding
to that `justfile` recipe.

The idea of actually building was suggested in:
#1808 (comment)

However, this does not uncover any new breakages. And there has
been further improvement on #1808, including in the commits leading
up to this, as well as earlier, in 569c186 (#1909). Nonetheless, it
seems likely that some problems remain with some combinations of
crates and features that are not currently exercised in the MSRV
check. #1808 is most likely not yet fully fixed.

Author: EliahKagan

.github/workflows/msrv.yml

@@ -45,5 +45,5 @@ jobs:
         run: |
           # TODO(msrv): Use `cargo update --minimal-versions` when `--minimal-versions` is available.
           cargo +nightly update -Zminimal-versions
-      - name: Run some `cargo check` commands on `gix`
+      - name: Run some `cargo build` commands on `gix`
         run: just ci-check-msrv

Makefile

@@ -126,8 +126,8 @@ bench-gix-config:
 
 check-msrv-on-ci: ## Check the minimal support rust version for currently installed Rust version
 	rustc --version
-	cargo check --locked --package gix
-	cargo check --locked --package gix --no-default-features --features async-network-client,max-performance
+	cargo build --locked --package gix
+	cargo build --locked --package gix --no-default-features --features async-network-client,max-performance
 
 ##@ Maintenance
 

justfile

@@ -246,8 +246,8 @@ check-size:
 # Check the MSRV, *if* the toolchain is set and `Cargo.lock` is downgraded (used on CI)
 ci-check-msrv:
     rustc --version
-    cargo check --locked -p gix
-    cargo check --locked -p gix --no-default-features --features async-network-client,max-performance
+    cargo build --locked -p gix
+    cargo build --locked -p gix --no-default-features --features async-network-client,max-performance
 
 # Enter a nix-shell able to build on macOS
 nix-shell-macos: