st/egl: Remove.

st/egl: Remove.

Largely superseeded by src/egl, and
WGL/GLX_EXT_create_context_es_profile extensions.

Note this will break Android.mk with gallium drivers -- somebody
familiar with that build infrastructure will need to update it to use
gallium drivers through egl_dri2.

v2: Remove the _EGL_BUILT_IN_DRIVER_GALLIUM define from
src/egl/main/Android.mk; and update the src/egl/main/Sconscript to
create a SharedLibrary, add versioning, create symlink - copy the bits
from egl-static, per Emil Velikov.

Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>
v3: Disallow undefined symbols in libEGL.so.  Update release notes