Revert platform and kernel gcc to aosp 4.7.

There is zero scientific evidence any of this stuff does anything
to improve the user experience an any meaningful way. On the
contrary, there is plenty of evidence non-aosp toolchains break
binaries and produce library stack errors. Therefore, all voodoo,
alchemy, witchcraft, and Santaria are hereby abolished from the
Eos project.

Change-Id: I121cec4a0b780b831b5afdbecff5d76c6ccb9ce1