arm gcc: upgrade arm toolchain to 4.7-2013q1

See release notes here: https://launchpadlibrarian.net/135595402/release.txt

Compiles all flight code without issue.  Compared Freedom target for size.  Code size looks identical.

Haven't tested on any platforms.

@lilvinz: this update specifically mentions some gdb changes for FP registers.  Hopefully it plays nice with all of your openocd changes.