needed for musl-1.2.3
--- a/source/mupen64plus-video-glide64mk2/src/Glide64/Main.cpp
+++ b/source/mupen64plus-video-glide64mk2/src/Glide64/Main.cpp
@@ -1182,7 +1182,7 @@
     char strSstWinOpenExt[] ="grSstWinOpenExt";
     GRWINOPENEXT grSstWinOpenExt = (GRWINOPENEXT)grGetProcAddress(strSstWinOpenExt);
     if (grSstWinOpenExt)
-      gfx_context = grSstWinOpenExt ((FxU32)NULL,
+      gfx_context = grSstWinOpenExt ((FxU32)0,
       res_data,
       GR_REFRESH_60Hz,
       GR_COLORFORMAT_RGBA,
@@ -1192,7 +1192,7 @@
       1);   // 1 auxillary buffer
   }
   if (!gfx_context)
-    gfx_context = grSstWinOpen ((FxU32)NULL,
+    gfx_context = grSstWinOpen ((FxU32)0,
     res_data,
     GR_REFRESH_60Hz,
     GR_COLORFORMAT_RGBA,