[7.6] Backport gdbserver fix from mainline.

Fix compatibility with Android Bionic.
* linux-low.c (linux_qxfer_libraries_svr4): Ignore first entry even if
it is not empty.

http://sourceware.org/ml/gdb-cvs/2013-06/msg00065.html

Change-Id: I192ccc36ec0567c72613917681b510a89dce7be8

Author: Ben Cheng <bccheng@google.com>
Date:   Tue Jun 11 12:32:30 2013 -0700