glibc: disable pie hardening, limit to musl for now

pkgs/development/libraries/glibc/default.nix

@@ -35,7 +35,10 @@ callPackage ./common.nix { inherit stdenv; } {
     # The stackprotector and fortify hardening flags are autodetected by glibc
     # and enabled by default if supported. Setting it for every gcc invocation
     # does not work.
-    hardeningDisable = [ "stackprotector" "fortify" ];
+    hardeningDisable = [ "stackprotector" "fortify" ]
+    # XXX: Not actually musl-speciic but since only musl enables pie by default,
+    #      limit rebuilds by only disabling pie w/musl
+      ++ stdenv.lib.optional stdenv.hostPlatform.isMusl "pie";
 
     # When building glibc from bootstrap-tools, we need libgcc_s at RPATH for
     # any program we run, because the gcc will have been placed at a new