package/apr-util: use post-prepare hook

package/apr-util: use post-prepare hook

Original APR_UTIL_FIX_RULES_MK_LIBTOOL tweaked libtool and rules.mk.

libtool is provided by a dependency (apr). It needs to be tweaked
and, as an apr-util external file, this tweak is relevant in
<PKG>_POST_PREPARE_HOOKS.

rules.mk is generated by apr-util configure step and it is private
to apr-util. The modification performed needs to be kept in
<PKG>_POST_CONFIGURE_HOOKS.

This commit splits original APR_UTIL_FIX_RULES_MK_LIBTOOL and
attaches each part to the correct hook.

Signed-off-by: Herve Codina <herve.codina@bootlin.com>
Reviewed-by: Yann E. MORIN <yann.morin.1998@free.fr>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>