acpi-build: fix support for glib < 2.22

glib < 2.22 does not have g_array_get_element_size,
limit it's use (to check all elements are 1 byte
in size) to newer glib.

This fixes build on RHEL 5.3.

Reported-by: Richard Henderson <rth@redhat.com>
Reported-by: Erik Rull <erik.rull@rdsoftware.de>
Tested-by: Richard Henderson <rth@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Message-id: 20131125220039.GA16386@redhat.com
Signed-off-by: Anthony Liguori <aliguori@amazon.com>
