* mod_ssl: restore argument structure for exec-type SSLPassPhraseDialog

        programs, and implement a special merging algorithm for
             SSLCertificate[Key]File to emulate the behavior in versions <= 2.4.7



git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1593003 13f79535-47bb-0310-9956-ffa450edef68