internal/rosa/gnu: gcc set with-multilib-list as needed

This breaks riscv64.

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

internal/rosa/gnu.go

@@ -1186,6 +1186,13 @@ func (t Toolchain) newGCC() (pkg.Artifact, string) {
 		version  = "15.2.0"
 		checksum = "TXJ5WrbXlGLzy1swghQTr4qxgDCyIZFgJry51XEPTBZ8QYbVmFeB4lZbSMtPJ-a1"
 	)
+
+	var configureExtra []KV
+	switch runtime.GOARCH {
+	case "amd64", "arm64":
+		configureExtra = append(configureExtra, KV{"with-multilib-list", "''"})
+	}
+
 	return t.NewPackage("gcc", version, pkg.NewHTTPGetTar(
 		nil, "https://ftp.tsukuba.wide.ad.jp/software/gcc/releases/"+
 			"gcc-"+version+"/gcc-"+version+".tar.gz",
@@ -1351,9 +1358,8 @@ ln -s system/lib /work/
 		// it also saturates the CPU for a consequential amount of time.
 		Flag: TExclusive,
 	}, &MakeHelper{
-		Configure: []KV{
+		Configure: append([]KV{
 			{"disable-multilib"},
-			{"with-multilib-list", `""`},
 			{"enable-default-pie"},
 			{"disable-nls"},
 			{"with-gnu-as"},
@@ -1361,7 +1367,7 @@ ln -s system/lib /work/
 			{"with-system-zlib"},
 			{"enable-languages", "c,c++,go"},
 			{"with-native-system-header-dir", "/system/include"},
-		},
+		}, configureExtra...),
 		Make: []string{
 			"BOOT_CFLAGS='-O2 -g'",
 			"bootstrap",