Fix a cosmetic issue where OpenSSL 0.9.7 will dump the error stack

during pass phrase entry.

* ssl_engine_pphrase.c (ssl_pphrase_Handle): Clear the OpenSSL error
stack before reading the private key.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk/modules/ssl@101515 13f79535-47bb-0310-9956-ffa450edef68