minor cleanup for watcom _inline keyword.

include/SDL_bits.h

@@ -48,7 +48,7 @@ extern "C" {
  *  \return the index of the most significant bit, or -1 if the value is 0.
  */
 #if defined(__WATCOMC__) && defined(__386__)
-extern _inline int _SDL_bsr_watcom (Uint32);
+extern __inline int _SDL_bsr_watcom(Uint32);
 #pragma aux _SDL_bsr_watcom = \
     "bsr eax, eax" \
     parm [eax] nomemory \