config/debug/gdb: add 7.7.1

Also remove the unneeded select in 7.7

Signed-off-by: Cody P Schafer <dev@codyps.com>
scripts/addToolVersion: fix for gdb versions >= 7.2

Signed-off-by: Cody P Schafer <dev@codyps.com>
scripts/addToolVersion: simpily gcc handling and fix for gcc-4.9.X (and later)