matchbox: apply libtool patch to matchbox-desktop

matchbox-desktop fails to build because it tries to read
/usr/lib/libxcb.la, which doesn't exist on a very basic system with no
development files instead. The buildroot-libtool.patch must therefore
be applied.

Unfortunately, matchbox doesn't yet use the autotools infrastructure,
so we have to manually apply the patch.

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