egl: Kill macro _EGL_DECLARE_MUTEX

egl: Kill macro _EGL_DECLARE_MUTEX

Replace all occurences of the macro with its expansion.

It seems that the macro intended to provide cross-platform static mutex
intialization. However, it had the same definition in all pre-processor
paths:
    #define _EGL_DECLARE_MUTEX(m) _EGLMutex m = _EGL_MUTEX_INITIALIZER

Therefore this abstraction obscured rather than helped.

Signed-off-by: Chad Versace <chad.versace@linux.intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>