glapi: Do not use glapioffsets.h.

glapioffsets.h exists for the same reason as glapidispatch.h does.  It
is of no use to glapi.  This commit also drops the use of glapioffsets.h
in glx as glx is considered an extension to glapi when it comes to
defining public GL entries.

src/mapi/glapi/gen/glX_proto_send.py

@@ -993,6 +993,9 @@ extern HIDDEN NOINLINE FASTCALL GLubyte * __glXSetupVendorRequest(
 					asdf = func.static_glx_name(n)
 					if asdf not in func.static_entry_points:
 						print 'extern HIDDEN %s gl%s(%s);' % (func.return_type, asdf, params)
+						# give it a easy-to-remember name
+						if func.client_handcode:
+							print '#define gl_dispatch_stub_%s gl%s' % (n, asdf)
 					else:
 						print 'GLAPI %s GLAPIENTRY gl%s(%s);' % (func.return_type, asdf, params)