community/qemu: limit lto jobs to 4 instead of nproc

samurai doesn't implement make jobserver so auto is nproc*nproc of total jobs

community/qemu/APKBUILD

@@ -305,7 +305,7 @@ _compile_common() {
 		export CFLAGS="${CFLAGS/-Os/-O2}"
 		;;
 	*)
-		export CFLAGS="${CFLAGS/-Os/-O2} -flto=auto"
+		export CFLAGS="${CFLAGS/-Os/-O2} -flto=4"
 		;;
 	esac