libglib2: needs autoreconf

libglib2: needs autoreconf

Patch 0002-disable-tests.patch modifies Makefile.am, so we have to
autoreconf. It hasn't been seen until now, but becomes very clear
since the bump of automake to 1.15.1, as we're seeing build failures
such as:

configure.ac:66: error: version mismatch.  This is Automake 1.15.1,
configure.ac:66: but the definition used by this AM_INIT_AUTOMAKE
configure.ac:66: comes from Automake 1.15.  You should recreate
configure.ac:66: aclocal.m4 with aclocal and run automake again.

Fixes:

  http://autobuild.buildroot.net/results/3402357d8e90f1866dfeaee7bb61119d80dc8bcb/

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>