build: use AC_ARG_WITH for zlib
build: use AC_ARG_WITH for zlib

Since it selects an external dependency for inclusion, AC_ARG_WITH
is preferred (autoconf.info 15.2 "Working with external software").

lpereira/kmod,lucasdemarchi/kmod,pmmccorm/kmod,Distrotech/kmod,Distrotech/kmod,lpereira/kmod,lucasdemarchi/kmod,lpereira/kmod,Distrotech/kmod,pmmccorm/kmod,pmmccorm/kmod,lucasdemarchi/kmod