cc/gcc: avoid passing --enable-multilib (take 2)

The previous patch (cset b61a1b1, cc/gcc: avoid passing --enable-multilib)
only fixed the core backend, and missed the final backend.

This patch does the same as b61a1b1, but for the final backend.

Signed-off-by: Cody P Schafer <dev@codyps.com>
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
cc/gcc: add 4.9.1

Signed-off-by: Cody P Schafer <dev@codyps.com>
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)

Signed-off-by: Cody P Schafer <dev@codyps.com>