Force speed irrelevant calls to get/put_symbol() to be noinline.

Force speed irrelevant calls to get/put_symbol() to be noinline.
We need to change decode_line to always_inline because gcc decided not to inline
it anymore once we force some calls to get/put_symbol() to be non inlined and
this decission of gcc would lead to a 10% overall speed loss.
100k smaller object file, no speed change

git-svn-id: file:///var/local/repositories/ffmpeg/trunk@18673 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b