apr_file_write, windows: Unlock the file in seek error path.

Sumitted by: @296995966 on github.
Github: closes #42



git-svn-id: https://svn.apache.org/repos/asf/apr/apr/trunk@1916276 13f79535-47bb-0310-9956-ffa450edef68

file_io/win32/readwrite.c

@@ -470,6 +470,7 @@ APR_DECLARE(apr_status_t) apr_file_write(apr_file_t *thefile, const void *buf, a
                 }
                 rc = apr_file_seek(thefile, APR_END, &offset);
                 if (rc != APR_SUCCESS) {
+                    apr_file_unlock(thefile);
                     if (thefile->flags & APR_FOPEN_XTHREAD) {
                         apr_thread_mutex_unlock(thefile->mutex);
                     }