Fix the vertexloader on non-x86 targets.

When I dropped ARM from a generic target, this caused the vertexloader to try using the JIT path.
Instead of !_M_GENERIC, check for _M_X86 instead. Since it is only for the x86 target
Merge pull request #489 from Sonicadvance1/Fix-NonX86

Fix the vertexloader on non-x86 targets.