Evas: Remove a useless ifdef that was causing dead code.

Evas: Remove a useless ifdef that was causing dead code.
You can't compile a gl_common .c file based on whether or not the SDL
header was included. The .c file will result in only one .o and since
the Evas_Engine_Sdl.h is not included by evas_gl_context.c itself, then
that ifdef will never be true.
gl_common should request a callback function pointer from the evas engine
for doing symbol resolution. This needs a refactor.

git-svn-id: svn+ssh://svn.enlightenment.org/var/svn/e/trunk/evas@64086 7cbeb6ba-43b4-40fd-8cce-4c39aea84d33