Allow setting connection pool parameters for Memcache server connections

[rpluem-vf]

• ChangeLog: Document change
• auth_openidc.conf Document the new directives OIDCMemCacheConnectionsMin OIDCMemCacheConnectionsSMax OIDCMemCacheConnectionsHMax OIDCMemCacheConnectionsTTL
• src/cache/memcache.c oidc_cache_memcache_post_config: Use the new parameters or use defaults when calling apr_memcache_server_create
• src/config.c oidc_set_uint32_slot: New function to set an apr_uint32_t value in the server config oidc_set_timeout_slot: New function to set an 32 bit uint timeout slot in the server config oidc_create_server_config: Init additional fields oidc_merge_server_config: Merge additional fields Declare the new directives OIDCMemCacheConnectionsMin OIDCMemCacheConnectionsSMax OIDCMemCacheConnectionsHMax OIDCMemCacheConnectionsTTL
• src/mod_auth_openidc.h Add new fields to struct oidc_cfg
• test/stub.c Add new stubs from httpd API: ap_mpm_query ap_timeout_parameter_parse