begin_code: Solaris Studio has `__has_attribute` defined by isn't usable here.

Fixes #10095.

include/begin_code.h

@@ -172,7 +172,7 @@
     (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 202000L)
 #define SDL_FALLTHROUGH [[fallthrough]]
 #else
-#if defined(__has_attribute)
+#if defined(__has_attribute) && !defined(__SUNPRO_C) && !defined(__SUNPRO_CC)
 #define SDL_HAS_FALLTHROUGH __has_attribute(__fallthrough__)
 #else
 #define SDL_HAS_FALLTHROUGH 0