mesa: Drop dead #include "sparc/sparc.h"

sparc.h was removed in when the classic drivers were removed. It only
contained a prototype for _mesa_init_all_sparc_transform_asm() which
wasn't even called by context.c. Remove the #include to fix the build on
sparc.

Fixes: e030d5ba8a ("mesa: Delete libmesa_classic")
Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/6425
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/16765>

src/mesa/main/context.c

@@ -143,10 +143,6 @@
 #include "macros.h"
 #include "git_sha1.h"
 
-#ifdef USE_SPARC_ASM
-#include "sparc/sparc.h"
-#endif
-
 #include "compiler/glsl_types.h"
 #include "compiler/glsl/builtin_functions.h"
 #include "compiler/glsl/glsl_parser_extras.h"