Switching glibc_version.sh to use git.
Switching glibc_version.sh to use git.

Using the git hash in place of the svn revision.

BUG=https://code.google.com/p/nativeclient/issues/detail?id=3928
TEST=None
TBR=ncbray@chromium.org

Review URL: https://codereview.chromium.org/794583005

git-svn-id: 721b910a23eff8a86f00c8fd261a7587cddf18f8@14270 fcba33aa-ac0c-11dd-b9e7-8d5594d729c2

sbc100/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client