postgresql: Respect dontDisableStatic

pkgs/servers/sql/postgresql/default.nix

@@ -58,6 +58,7 @@ let
         # Prevent a retained dependency on gcc-wrapper.
         substituteInPlace "$out/lib/pgxs/src/Makefile.global" --replace ${stdenv.cc}/bin/ld ld
 
+        if [ -z "''${dontDisableStatic:-}" ]; then
           # Remove static libraries in case dynamic are available.
           for i in $out/lib/*.a; do
             name="$(basename "$i")"
@@ -65,6 +66,7 @@ let
               rm "$i"
             fi
           done
+        fi
       '';
 
     postFixup = lib.optionalString (!stdenv.isDarwin)