Let the location of APR[-Util] and PCRE libs and

Let the location of APR[-Util] and PCRE libs and
includes default to the same prefix where this package
is installed, generally eliminating four required settings
for users.

APR trunk vs. APR[-Util] 1.x is selected automatically,
as is PCRE debug vs. release.  (But if you have both
debug and release builds of PCRE you may not like the choice,
and will need to override.

Add a bunch of gory details about the build to the configuration
summary.

Document that static PCRE builds aren't yet supported (before
or after this commit).

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1519270 13f79535-47bb-0310-9956-ffa450edef68