internal/rosa/cmake: optional variant string

This improves consistency with other helpers and removes the usually unnecessary variant suffix.

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

internal/rosa/llvm.go

@@ -167,7 +167,7 @@ ln -s ld.lld /work/system/bin/ld
 		)
 	}
 
-	return t.NewViaCMake("llvm", version, variant, t.NewPatchedSource(
+	return t.NewViaCMake("llvm", version, t.NewPatchedSource(
 		"llvmorg", version, pkg.NewHTTPGetTar(
 			nil, "https://github.com/llvm/llvm-project/archive/refs/tags/"+
 				"llvmorg-"+version+".tar.gz",
@@ -175,6 +175,8 @@ ln -s ld.lld /work/system/bin/ld
 			pkg.TarGzip,
 		), true, attr.patches...,
 	), &CMakeAttr{
+		Variant: variant,
+
 		Cache:  slices.Concat(cache, attr.cmake),
 		Append: cmakeAppend,
 		Prefix: attr.prefix,