r600 & nouveau XvMC libs have same soname
Building Mesa 20.1.4 with XvMC results in two libraries having same SONAME:
$ objdump -p libXvMC{r600,nouveau}.so.1.0.0 | grep SONAME
SONAME libXvMCgallium.so.1
SONAME libXvMCgallium.so.1
This in turn results in ldconfig creating symlink randomly to one of those libs. Surprisingly Mesa installs symlinks called "libXvMCr600.so.1" and "libXvMCnouveau.so.1" but they're not in line with SONAME.