zsnes: fix the build against gcc-15 (#477292)

pkgs/applications/emulators/zsnes/default.nix

@@ -60,7 +60,8 @@ stdenv.mkDerivation {
   # Workaround build failure on -fno-common toolchains:
   #   ld: initc.o:(.bss+0x28): multiple definition of `HacksDisable'; cfg.o:(.bss+0x59e3): first defined here
   # Use pre-c++17 standard (c++17 forbids throw annotations)
-  env.NIX_CFLAGS_COMPILE = "-fcommon -std=c++14";
+  # Use pre-c23: chips/dsp3emu.c:31:23: error: 'bool' cannot be defined via 'typedef'
+  env.NIX_CFLAGS_COMPILE = "-fcommon -std=c++14 -std=gnu17";
 
   preConfigure = ''
     cd src
@@ -70,6 +71,8 @@ stdenv.mkDerivation {
 
   configureFlags = [ "--enable-release" ];
 
+  enableParallelBuilding = true;
+
   postInstall = ''
     function installIcon () {
         mkdir -p $out/share/icons/hicolor/$1/apps/