Wrapped some macro params in parentheses for alloca wrappers.

  Thansk, Suzuki Masahiro.

--HG--
branch : SDL-1.2
extra : convert_revision : svn%3Ac70aab31-4412-0410-b14c-859654838e24/branches/SDL-1.2%402240

include/SDL_stdinc.h

@@ -181,10 +181,10 @@ extern DECLSPEC void SDLCALL SDL_free(void *mem);
 # endif
 #endif
 #ifdef HAVE_ALLOCA
-#define SDL_stack_alloc(type, count)    (type*)alloca(sizeof(type)*count)
+#define SDL_stack_alloc(type, count)    (type*)alloca(sizeof(type)*(count))
 #define SDL_stack_free(data)
 #else
-#define SDL_stack_alloc(type, count)    (type*)SDL_malloc(sizeof(type)*count)
+#define SDL_stack_alloc(type, count)    (type*)SDL_malloc(sizeof(type)*(count))
 #define SDL_stack_free(data)            SDL_free(data)
 #endif