egl: These changes allow an eglBindAPI(EGL_OPENGL_ES_API) to succeed, and to work...

egl: These changes allow an eglBindAPI(EGL_OPENGL_ES_API) to succeed, and to work correctly with GLES1 and GLES2.

- egl_xdri.c just sets the EGL_OPENGL_ES_BIT as well as the
  EGL_OPENGL_BIT in ClientAPIsMask

- eglconfig.c allows the renderable type to include EGL_OPENGL_ES2_BIT
  as well as EGL_OPENGL_ES_BIT.

- egl_xlib.c sets the EGL_NATIVE_RENDERABLE attribute to EGL_FALSE for
  all softpipe configurations.  (Otherwise, an eglChooseConfig() that
  looks for particular values of EGL_NATIVE_RENDERABLE will fail.)