Add pattern to check for GCC 4.6

GCC 4.6 --version can return 4.6.x-google but also simply 4.6
as of https://android-review.googlesource.com/#/c/42028.
Add more pattern to detect it.

Change-Id: Ibf34fba9afdf01bd3eafc011cc4d059b59f25d3d