Update GDB revision
Update GDB revision

This brings in:
- codereview.settings
- GDB 7.4.1
- x86_64 data model and glibc support

BUG=
TEST=

Review URL: https://chromiumcodereview.appspot.com/10802014

git-svn-id: 721b910a23eff8a86f00c8fd261a7587cddf18f8@9170 fcba33aa-ac0c-11dd-b9e7-8d5594d729c2

sbc100/native_client,nacl-webkit/native_client,sbc100/native_client,nacl-webkit/native_client,sbc100/native_client,nacl-webkit/native_client,nacl-webkit/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client,nacl-webkit/native_client