Graph builder: Make duplicated filter detection stricter.

This let us blacklist filters more easily. It also prevents the external version of an internal filter to be added to the candidate filters list unless the internal filter is disabled.
Blacklist some filters that are known to be incompatible with DVB.

This includes the internal video decoder for now (refs #730).
Updated French translation.
Updated Polish translation.
Updated Basque translation.

Refs: #2890.
Fix some typos.
Prevent non translatable "static" string to be added to the text files.
update ffmpeg/config.h
include MIPS headers only when ARCH_MIPS is defined
remove the unneeded MIPS files
update ffmpeg (n0.8-19402-g5d2f2c7)

Notes: broken atm because our custom files need to be updated too

* libavcodec/h264_dxva.c
* libavcodec/h264_recov.c
* libavcodec/vc1_dxva.c