configure: honour --with-ocf instead of silently disabling OCF

[ThalesBarretto]

configure: honour --with-ocf instead of silently disabling OCF

Fixes: #4760

AC_ARG_WITH([ocf], …) set OCF_SUBDIR='ocf' only in the
action-if-not-given slot and left action-if-given empty. Any explicit
--with-ocf therefore ran the empty action and left OCF_SUBDIR unset, so
--with-ocf — the flag a packager uses to request the OCF resource
agents — silently disabled them, identically to --without-ocf. Only the
no-flag default built them. OCF_SUBDIR feeds SUBDIRS in
extras/Makefile.am, so the mishandled flag dropped extras/ocf from both
the build and the install.

The fix captures $withval in action-if-given, defaults with_ocf=yes,
and sets OCF_SUBDIR only when with_ocf is not no — the same
value-discard idiom already fixed for --with-{tcmalloc,libtirpc,ipv6-default}
in a249d07656. The backwards --without-ocf help text is corrected too.

Behaviour (install-verified)

Real out-of-source configure + make install A/B on devel; the two
DESTDIR trees differ by exactly …/lib/ocf/resource.d/glusterfs/{glusterd,volume}:

./configure input	agents before	agents after
(no flag — default)	installed	installed
--without-ocf	absent	absent
--with-ocf=no	absent	absent
--with-ocf	absent (bug)	installed
--with-ocf=yes	absent (bug)	installed
--with-ocf=<other>	absent	installed (as yes)

Only the affirmative --with-ocf[=…] path changes; the default and
--without-ocf are unchanged. Upstream glusterfs.spec.in never passes
--with-ocf (only nothing, or --without-ocf under --without server),
so packaging is unaffected.

Provenance

commit	date · author	--with-ocf	default
40f5ce0db6	2012-02-20 · Florian Haas	builds	off (opt-in)
0f851d4dd8	2012-11-06 · Niels de Vos	disables	on
(this patch)	—	builds	on

The option was born working as an opt-in flag in 40f5ce0db6, where
AM_CONDITIONAL(WITH_OCF, [test "$with_ocf" = "yes"]) read the value the
argument parser set. 0f851d4dd8 flipped OCF on by default and switched the
plumbing to OCF_SUBDIR/SUBDIRS, but dropped that read of $with_ocf —
leaving the affirmative --with-ocf path dead. Untouched since.

Risk

Build-system only; no runtime code touched. Default behaviour (agents built)
is unchanged.