util: move string_to_uint_map to glsl

util: move string_to_uint_map to glsl

The functionality is used by glsl and mesa. With the latter already
depending on the former.

With this in place the src/util/ static library libmesautil.la no longer
has a C++ dependency. Thus objects which use it (like libEGL) don't need
the C++ link.

Cc: "17.2" <mesa-stable@lists.freedesktop.org>
Fixes: 02cc35937277 ("egl/wayland: Use linux-dmabuf interface for buffers")
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=101851
Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
Suggested-by: Jason Ekstrand <jason@jlekstrand.net>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Tested-by: Mike Lothian <mike@fireburn.co.uk>
Tested-by: James Harvey <lothmordor@gmail.com>