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

Fixes #10095.

(cherry picked from commit d96f1d5360be6dd5f57c3f100deb80c7f39da2a5)

include/SDL3/SDL_begin_code.h

@@ -165,7 +165,7 @@
     (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 202000L)
 #define SDL_FALLTHROUGH [[fallthrough]]
 #else
-#ifdef __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