run libtool from the apr install directory (in case that is different

from the apache install directory)

further changes are needed to automatically pick up apr and apr-util
include directories; for now, "-Wc,-I/path" needs to be added to the
apxs -c invocation to work around that problem


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@99213 13f79535-47bb-0310-9956-ffa450edef68