Eliminate a warning in a failure case.

third_party/mesa/MesaLib/src/mapi/glapi/glapi_nop.c

 /*
  * Mesa 3-D graphics library
  * Version:  7.8
  *
  * Copyright (C) 1999-2008  Brian Paul   All Rights Reserved.
  * Copyright (C) 2010  VMware, Inc.  All Rights Reserved.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a
  * copy of this software and associated documentation files (the "Software"),
  * to deal in the Software without restriction, including without limitation
@@ skipping 68 matching lines @@
 }
 
 /*
  * Defines for the glapitemp.h functions.
  */
 #define KEYWORD1 static
 #define KEYWORD1_ALT static
 #define KEYWORD2 GLAPIENTRY
 #define NAME(func)  NoOp##func
 #define DISPATCH(func, args, msg)  Warn(#func);
-#define RETURN_DISPATCH(func, args, msg)  Warn(#func); return 0
+#define RETURN_DISPATCH(type, func, args, msg)  Warn(#func); return (type)0
 
 
 /*
  * Defines for the table of no-op entry points.
  */
 #define TABLE_ENTRY(name) (_glapi_proc) NoOp##name
 
 #else
 
-static int
+void
 NoOpGeneric(void)
 {
 #if !defined(_WIN32_WCE)
    if (getenv("MESA_DEBUG") || getenv("LIBGL_DEBUG")) {
       fprintf(stderr, "GL User Error: calling GL function without a rendering context\n");
    }
 #endif
-   return 0;
 }
 
 /**
  * This is called if the user somehow calls an unassigned GL dispatch function.
  */
 static GLint
 NoOpUnused(void)
 {
-   return NoOpGeneric();
+   NoOpGeneric();
+   return 0;
 }
 
 /*
  * It is necessary to generate custom no-op entry points at least on
  * Windows, where the __stdcall calling convention is used (callee
  * cleans the stack). This calling convention can not tolerate a
  * mismatch between the numbers of arguments in caller and callee.
  */
 #define KEYWORD1 static
 #define KEYWORD1_ALT static
 #define KEYWORD2 GLAPIENTRY
 #define NAME(func)  NoOp##func
 #define DISPATCH(func, args, msg)  NoOpGeneric();
-#define RETURN_DISPATCH(func, args, msg)  return NoOpGeneric();
+#define RETURN_DISPATCH(type, func, args, msg)  NoOpGeneric(); return (type)0
 
 /*
  * Defines for the table of no-op entry points.
  */
 #define TABLE_ENTRY(name) (_glapi_proc) NoOp##name
 
 #endif
 
 #define DISPATCH_TABLE_NAME __glapi_noop_table
 #define UNUSED_TABLE_NAME __unused_noop_functions
 
 #include "glapi/glapitemp.h"