[Patch, i386] Turn on -fschedule-insns and -fsched-pressure by default for x86-64

[Fang, Changpeng]

> "-fschedule-insns -fsched-pressure" isn't well tested:
We have tested the gcc testsuite and SPEC cpu benchmarks.


> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46829
Bug 46829 does not appear in 4.6 trunk, and the patched compiler does not
not has this bug either.

>Have you run "-fschedule-insns -fsched-pressure" on gcc testsuite?
Yes, gcc testsuite testing passes for both -O2 and -O3 bootstrapped compilers.

Thanks,

Changpeng

>--
>H.J.