Debug stub: enable gdb tests for x86_64 glibc
Debug stub: enable gdb tests for x86_64 glibc

With updated GDB, tests now pass with glibc as well.

BUG=http://code.google.com/p/nativeclient/issues/detail?id=2896
TEST=run_gdb_stepi_after_break_test run_gdb_break_continue_thread_test

Review URL: https://chromiumcodereview.appspot.com/10796013

git-svn-id: 721b910a23eff8a86f00c8fd261a7587cddf18f8@9175 fcba33aa-ac0c-11dd-b9e7-8d5594d729c2

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