Try "--with-apache=/usr/local/apache" but I doubt it'll work. Since you're trying to install php as a static apache module you'll need the apache sources because php must build it's module in the apache/modules directory. So you must use "--with-apache=/path/to/apache-source".
Or you can build php as a dso (if apache is configured to support dso) using "--with-apxs(2)=/usr/local/apache/bin/apxs" (note: (2) is for apache2)
Take a look here
for more details.