util: use anonymous file for memory fd creation

The original implementation in os_memory_fd.c always uses memfds.
Replace this by using the already existing os_create_anonymous_file in
order to support older systems or systems without memfd.

Fixes: 1166ee9caf3 ("gallium: add utility and interface for memory fd allocations")

Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/13331>
(cherry picked from commit 4856586ac605e89ee6c128b1a190f000311b49ba)
3 files changed