Use SSE3 in 32-bit x86 binaries
Pros:
- Seems to fix strange issue on AMD processors where the compiled binary has a chance to have 2x slower slope rendering in software mode
- Improves OpenGL performance on AMD processors
- Timedemo shows tiny performance increase on Intel Atom N270 on both renderers
- Timedemo shows tiny performance increase on Intel Core i7-4770HQ on software mode
- Slopes get 20% faster on this CPU
Cons:
- CPUs older than 15 years will not run the executable.
CMake changes are untested, I don't have CMake.