Tested-by: Emil Velikov <emil.l.velikov@gmail.com>
Reviewed-and-Tested-by: Andreas Boll <andreas.boll.dev@gmail.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Specifically, move all or most of
glapi/glapi.c to mapi/u_current.c,
glapi/glapi_execmem.c to mapi/u_execmem.c,
glapi/glthread.[ch] to mapi/u_thread.[ch]
and remove their dependencies on core Mesa headers.
