internal/rosa: parallel autoconf tests

These take forever and run sequentially by default for some reason.

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

internal/rosa/gnu.go

@@ -64,7 +64,10 @@ cd "$(mktemp -d)"
 /usr/src/autoconf/configure \
 	--prefix=/system \
 	--build="${ROSA_TRIPLE}"
-make "-j$(nproc)" check
+make \
+	"-j$(nproc)" \
+	TESTSUITEFLAGS="-j$(nproc)" \
+	check
 make DESTDIR=/work install
 `, pkg.Path(AbsUsrSrc.Append("autoconf"), false, pkg.NewHTTPGetTar(
 		nil,