add support for OpenBSD in ffmpeg

add openbsd config files

ffmpeg.gyp:
  - use openbs config files
  - disable -fno-signed-zeros because our gcc does not support it.

BUG=
TEST=

Patch by Robert Nagy <robert.nagy@gmail.com>
Review URL: http://codereview.chromium.org/8275011

git-svn-id: http://src.chromium.org/svn/trunk/deps/third_party/ffmpeg/source@106959 4ff67af0-8c30-449e-8e8b-ad334ec8d88c
5 files changed