* mod_ssl: Fix spurious errors when loading certificate chain

  2.2.x uses a home grown version of SSL_CTX_use_certificate_chain_file
  called SSL_CTX_use_certificate_chain() which also needs the
  ERR_clear_error() call.
  trunk patch: N/A, but similar to https://svn.apache.org/r1588427

PR: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=794383
Submitted by: sf
Reviewed by: sf, rpluem, ylavic



git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.2.x@1700409 13f79535-47bb-0310-9956-ffa450edef68