Add GCC_CONFIG option to enable default PIE (#1418)

This was removed in #1346 for unknown reasons. I'm adding it back in.

Author: Emilgardis

docker/musl.sh

@@ -51,6 +51,7 @@ main() {
         LINUX_HEADERS_SITE="${linux_headers_site}" \
         LINUX_VER="${linux_ver}" \
         OUTPUT=/usr/local/ \
+        "GCC_CONFIG += --enable-default-pie" \
         "${@}"
 
     purge_packages