Remove glibc-2.15

All uses of glibc 2.15 were replaced over a week ago. Everything appears
to be running along smoothly at this point, so we can now remove the
old.

Bug: 111358231
Test: repo sync && lunch aosp_marlin-eng && m (same on internal master,
      s/aosp_marlin-eng/marlin-eng/`)

Change-Id: Ie4333fe7fb5b9b6dd1f3bf7189ac075394f89eb1
1 file changed