mod_ssl: Let modssl_set_io_callbacks() whether which callback is needed.

mod_ssl: Let modssl_set_io_callbacks() whether which callback is needed.

* modules/ssl/ssl_private.h:
  Add conn_rec and server_rec args to modssl_set_io_callbacks().

* modules/ssl/ssl_engine_io.c(modssl_set_io_callbacks):
  Don't set modssl_io_cb for log levels below TRACE4.

* modules/ssl/ssl_engine_io.c(ssl_io_filter_init),
  modules/ssl/ssl_engine_kernel.c(ssl_find_vhost):
  Call modssl_set_io_callbacks() unconditionally.

* modules/ssl/ssl_engine_io.c(modssl_io_cb):
  While at it, (cmd & BIO_CB_WRITE) is enough to differentiate a
  write from read.

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1918883 13f79535-47bb-0310-9956-ffa450edef68