gcc: Backport patch to make LTO builds more reproducible

Backport ustream gcc patch that enables -fdebug-prefix-map to cover
additional cases with LTO enabled to make LTO builds more reproducible.

[YOCTO #14481]

Signed-off-by: Tony Battersby <tonyb@cybernetics.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>