Latest clang does not emit errors about unknown warning options,
but it does spam the compile output with warnings. Silence those
warnings.

* build/ac-macros/compiler.m4
  (SVN_CC_MODE_SETUP): Add -Wno-unknown-warning-option to default C flags.
  (SVN_CXX_MODE_SETUP): Likewise for default C++ flags.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1480080 13f79535-47bb-0310-9956-ffa450edef68
Spell-check translated error messages.

* subversion/include/svn_error_codes.h
  SVN_ERR_NO_APR_MEMCACHE):
* subversion/libsvn_client/add.c
  (mkdir_urls):
* subversion/libsvn_client/merge.c
  (check_repos_match, get_wc_explicit_mergeinfo_catalog, do_file_merge):
* subversion/libsvn_client/ra.c
  (push_wc_prop):
* subversion/libsvn_ra_serf/serf.c
  (load_http_auth_types):
    Copyedit some error strings.

* subversion/libsvn_subr/cache-membuffer.c
  (svn_cache__membuffer_cache_create):
    Don't try to translate the string "OOM".


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1480082 13f79535-47bb-0310-9956-ffa450edef68