internal/rosa/gnu: mpc fetch source tarball

This does not have submodules, so the overhead of git is unnecessary.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/rosa/gnu.go

@@ -1052,10 +1052,11 @@ func init() {
 func (t Toolchain) newMPC() (pkg.Artifact, string) {
 	const (
 		version  = "1.4.1"
-		checksum = "wdXAhplnS89FjVp20m2nC2CmLFQeyQqLpQAfViTy4vPxFdv2WYOTtfBKeIk5_Rec"
+		checksum = "ZffaZyWkvIw0iPvRe5EJ7O-VvHtSkbbb3K_7SgPtK810NvGan7nbF0T5-6tozjQN"
 	)
-	return t.NewPackage("mpc", version, t.newTagRemote(
-		"https://gitlab.inria.fr/mpc/mpc.git",
+	return t.NewPackage("mpc", version, newFromGitLab(
+		"gitlab.inria.fr",
+		"mpc/mpc",
 		version, checksum,
 	), &PackageAttr{
 		// does not find mpc-impl.h otherwise