mesa: drop .so files for GLVND ICD libraries

mesa: drop .so files for GLVND ICD libraries

If GLVND is enabled, Mesa provides two ICD libaries, libEGL_mesa.so.0
and libGLX_mesa.so.0. During the installation it also creates two extra
symlinks, libEGL_mesa.so and libGLX_mesa.so, however those symliks are
unnecessary and useless as nothing will ever link to those ICD archives.
Remove them from the install dir, which also makes package
libglx-mesa-dev disappear (it contained only this symlink).

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>