debug/gdb: update Linaro GDB revision for 2013.05

Update Linaro GDB with the latest available revision.

Signed-off-by: "Michael Hope" <michaelh@juju.net.nz>
Message-Id: <bea34f42853a9d87a628.1372452016@localhost>
Patchwork-Id: 255667

reporter_name="Ioannis E. Venetis"

reporter_url="http://sourceware.org/ml/crossgcc/2011-05/msg00005.html"

reporter_comment=""