GCC < 5 used to reserve the ebx register for PIC (position-independent
code) metadata. This meant that we needed to save the state of ebx
before calling cpuid (fixed in #2675)
However, the original patch from 03eaf9b461 did not force a particular
register to store this value in. Following the GCC 5 upgrade, GCC
stopped reserving ebx, and that register silently got used instead. The
code became non-sensical, and our ASM __cpuidex started returning random
garbage in edx.
Since we now only support GCC7 and above, the PIC-specific branch is no
longer necessary and is removed.
Fixes#6028. The assertion was a result of random data in ebx.
Refs #2675 / reverts 6334ee3f8b and reverts 03eaf9b461.
Patch by: nwtour
Comments by: vladislavbelov
Differential Revision: https://code.wildfiregames.com/D3575
This was SVN commit r25405.