When no specific location of openssl is given, we need to check the

When no specific location of openssl is given, we need to check the
places where people install upgraded software first, since otherwise
we will get the older versions installed by the OS distribution.  That's
very bad for us because we are requiring a version of openssl that is
more recent than most of the Linux distros.

When finding the openssl helper program, check both the PATH and the default
install dirs, since openssl isn't normally included on a user's path.

Use APR_ADDTO to add to the make macros in order to avoid duplicates.

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@89053 13f79535-47bb-0310-9956-ffa450edef68