Bootstrapping GCC in PGO, LTO, and SMS modes

I tried to bootstrap current GCC trunk and our latest gcc-linaro-4.6 in profile guided, link time optimisation, and SMS modes. The results are here: https://wiki.linaro.org/MichaelHope/Sandbox/PGOLTOSMSStatus1

Short story: you can't bootstrap in LTO or PGO on ARM as they run out of memory. i686 LTO is broken on trunk and gcc-linaro-4.6. SMS is fine in general.

I'll run these once a week and keep an eye on them. A -fwhopr instead of -flto may help on ARM. I don't know why the PGO build runs out of memory.

-- Michael