media-video/ffmpeg: Pass disable optimization to configure.

media-video/ffmpeg: Pass disable optimization to configure.

This is only useful for hardcoded CFLAGS. We use optflags that override them anyway. However, some configure checks run with fomit-frame-pointer when this is enabled.
This lures the build system it has enough registers to build some inline asm on x86 and then causes build failures.

Closes: https://bugs.gentoo.org/671746
Closes: https://bugs.gentoo.org/645778
Package-Manager: Portage-2.3.51, Repoman-2.3.12
RepoMan-Options: --force
Signed-off-by: Alexis Ballier <aballier@gentoo.org>