pytest_suite: fix startup failures and add missing Perl helper templates

pytest_suite: fix startup failures and add missing Perl helper templates

Three bugs fixed in the pytest framework:

1. cmodules.py: compiled C test modules were not rebuilt when apxs changed
   (e.g. upgrading from Apache 2.4 to 2.5). The staleness check now also
   compares the .so mtime against apxs itself, so a newer apxs always
   triggers a rebuild and prevents API-signature mismatches (AP24 vs AP25).
   Add clean_modules() to remove all apxs build artifacts (make clean
   equivalent), exposed as --clean-modules pytest option and routed only
   to pytest_suite (not pyhttpd) in run-all-tests.sh.

2. server.py: httpd was started without -DFOREGROUND, so the MPM parent
   forked and exited (code 0) before the port opened. The framework
   misread the fork-exit as a crash and killed the running daemon.
   Add -DFOREGROUND so the Popen process IS the httpd parent.

3. Missing Perl helper scripts: t/conf/extra.conf.in declares a prg-type
   RewriteMap (numbers-prg) whose program file did not exist, causing
   httpd to refuse to start. More broadly, all *.pl CGI scripts,
   ext_filter programs, rewrite-map programs, and the SSL passphrase
   helper referenced by the config and tests were absent.
   Add the full set of *.pl.PL source templates (copied from the
   httpd-tests framework), covering:
     - t/conf/ssl/httpd-passphrase.pl.PL
     - t/htdocs/apache/http_strict/send_hdr.pl.PL (new dir)
     - t/htdocs/modules/cgi/  (28 CGI scripts)
     - t/htdocs/modules/ext_filter/  (2 filter programs, new dir)
     - t/htdocs/modules/negotiation/query/test.pl.PL
     - t/htdocs/modules/rewrite/  (numbers, numbers2, db)
   generate_pl_scripts() regenerates the .pl executables from these
   templates at each test-session start with the correct local perl shebang.

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1934936 13f79535-47bb-0310-9956-ffa450edef68