tests: Rename vsynth2 to vsynth_lena

This avoids confusion with a growing number of vsynth tests

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
tests: Add vsynth2 which uses the new reference.pnm

The file is already present in git and by using it we can perform more tests
without the need of fate samples

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
lavc/dirac_arith: Only compile x86 asm if ARCH_X86 is set.

Fixes ticket #3544.
Also print GUIDs as shown in the Windows registry to ease debugging.
lavf/qcp: Print unknown GUID on error.