lzo: fix host-lzo build failure when config cache is filled

When the configuration cache has been filled with a value for
ac_cv_host, host-lzo fails to detect the target system name. This is
due to misbehaving code in the ./configure script. Therefore, we need
to autoreconf the package, which in turn requires :

 * a little fix to the configure.ac file
 * a little fix to src/Makefile.am
 * an extraction of important parts of aclocal.m4 into acinclude.m4

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