[SUGGESTION] Change x86 march flag to "pentium3"

-march=native was added as a feature to GCC 4.2 and just determines the architecture of the system that the compiler is running on. This is very sensible for people wanting to compile themselves. This won't be being used for the official build though as otherwise, let's say someone builds it native on a Core i7, it won't run on any less than a Core i3/i5/i7 processor.

Intel generally leads with new instruction sets and AMD follows, the big exception being x86-64 which went the other way. SSE was introduced by Intel for the Pentium 3 in 1999 but only implemented by AMD with the Athlon XP 1500+, Athlon 4 mobile processor 800MHz+ and Duron Morgan 900MHz+, all year 2001. Hence although a Pentium II 450MHz would be excluded, a 1.4GHz Athlon Thunderbird would also be excluded. Has anyone got something like this (or can overclock to this level) to test with? If it isn't playable anyway then might as well abandon support for anything non-SSE and get 1-2% better performance for the the person with the Athlon XP 1500+ to make it playable. SSE is quite influential in games.

As for newer instructions, the Pentium 4 introduced SSE2 but was only used by AMD for the Opteron and Athlon 64, hence it would exclude Athlon XP which would seem a bit harsh.