Merge r1769718, r1785943, r1786110, r1786119 from trunk:
add an <IfFile> config section like <IfDefine>
It allows a non httpd config file to be used as a marker directly in httpd.conf without hiding logic in a script in front of apachectl to do test -f and pass extra -D's.
This is something we've had in IBM's httpd distro for a little bit and hadn't remembered to share. I've seen some questions/config files come up in a few places lately that would benefit from this as an option.
Remove duplicate implementations of conditional section function. No functional change.
* server/core.c (start_cond_section): Factor out from start_if*. Adjust to use apr_strmemdup. (test_ifmod_section, test_iffile_section, test_ifdefine_section): Move container-specific tests into callbacks from start_if*. (core_cmds): Adjust <IfFile, <IfDefine, <IfModule to use start_cond_section with callbacks.
Add <IfDirective> and <IfSection>:
* server/core.c (test_ifdirective_section, test_ifsection_section): New callbacks. (core_cmds): Define new directives.
* include/http_config.h, server/config.c (ap_exists_directive): New function.
* include/ap_mmn.h: Bump MMN minor for above.
* docs/manual/mod/core.xml: Add docs.
* server/core.c (start_cond_section): Comment & variable name fixes, no functional change.