Fix format string warnings from gcc on amd64:

Fix format string warnings from gcc on amd64:

* modules/ssl/ssl_scache_dbm.c (ssl_scache_dbm_store):
Print apr_size_t using APR_SIZE_T_FMT.

* modules/ssl/ssl_engine_io.c (ssl_filter_write): Print difference
between sizes using APR_SSIZE_T_FMT, apr_size_t using APR_SIZE_T_FMT.

* modules/proxy/proxy_http.c (ap_proxy_http_request): Print
apr_uint64_t using APR_UINT64_T_HEX_FMT.

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk/modules/ssl@102037 13f79535-47bb-0310-9956-ffa450edef68