Log Message:
Update apache to apache-2.0.52.

Also added comment to www/apache2/Makefile.common to remind to
update checksum in devel/apr also.

No actual devel/apr changes seen.

Also removed www/apache2/patches/patch-ab because it is identical to
fix for security in new version.

Changes with Apache 2.0.52
  *) Use HTML 2.0 <hr> for error pages. PR 30732 [André Malo]
  *) Fix the global mutex crash when the global mutex is never allocated
     due to disabled/empty caches. [Jess Holle <jessh ptc.com>]
  *) Fix a segfault in the LDAP cache when it is configured switched
     off. [Jess Holle <jessh ptc.com>]
  *) SECURITY: CAN-2004-0811 (cve.mitre.org)
     Fix merging of the Satisfy directive, which was applied to
     the surrounding context and could allow access despite configured
     authentication.  PR 31315.  [Rici Lake <rici ricilake.net>]
  *) Fix the handling of URIs containing %2F when AllowEncodedSlashes
     is enabled.  Previously, such urls would still be rejected.
     [Jeff Trawick, Bill Stoddard]
  *) mod_mem_cache: Fixed race condition causing segfault because of memory being
     freed twice, or reused after being freed.
     [J. Clar, W. Stoddard, G. Ames]
  *) Add -l option to rotatelogs to let it use local time rather than
     UTC.  PR 24417.  [Ken Coar, Uli Zappe <uli ritual.org>]
  *) mod_log_config: Fix a bug which prevented request completion time
     from being logged for I_INSIST_ON_EXTRA_CYCLES_FOR_CLF_COMPLIANCE
     processing.  PR 29696.  [Alois Treindl <alois astro.ch>]