debug/gdb: update Linaro GDB revisions to 2012.12-1

Update Linaro GDB with the latest available revisions.

Signed-off-by: "Benoît Thébaudeau" <benoit.thebaudeau@advansee.com>
Message-Id: <b6c4a82286f9a3de3948.1355761104@advdt005-ubuntu>
Patchwork-Id: 206907

 reporter_name="Yann E. MORIN"

 reporter_url="http://ymorin.is-a-geek.org/projects/crosstool"

 reporter_comment="EXPERIMENTAL MIPS-64 n32 toolchain."