multimedia/ffmpeg: Exclude LTO from OPTIONS on i386.

Details:

• The low number of i386 leads to register exhaustion when compiling with LTO. Due to the decreasing popularity of 32 bit i386 machines which require hyper-optimised ffmpeg builds, the option is excluded from the builds for now.

PR: 257124
MFH: 2021Q3
(cherry picked from commit 0561f3e6355206d3ff81b2d9a69f62e10fc7f16e)