glapi: _glapi_create_table_from_handle: Set missing pointers to NoOp rather than...

glapi: _glapi_create_table_from_handle: Set missing pointers to NoOp rather than NULL

This change to _glapi_create_table_from_handle causes it to fill the dispatch
table with NoOps for unimplemented functionality.  This matches what is done
in indirect_init.c and also allows us to enable logging (when built with
-DDEBUG and the MESA_DEBUG or LIBGL_DEBUG environment variables are set) to
catch cases where clients are trying to use these unimplemented extentions.

Additionally, this fixes some gcc -pedantic warnings.

Signed-off-by: Jeremy Huddleston <jeremyhu@apple.com>