Fix compilation warning for 'strncpy' due string truncation

As per the GCC manual, calls to 'strn*' function family shall be
replaced by 'memcpy' when truncation (no null termination) is expected.

lib/MySQL_Session.cpp

@@ -8145,8 +8145,8 @@ char* MySQL_Session::get_current_query(int max_length) {
 		res = (char *) malloc(query_len + 1);
 		if (trunc_query) {
 			// for truncated queries, add three dots at the end
-			strncpy(res, query_ptr, query_len - 3);
-			strncpy(res + (query_len - 3), "...", 3);
+			memcpy(res, query_ptr, query_len - 3);
+			memcpy(res + (query_len - 3), "...", 3);
 		} else {
 			strncpy(res, query_ptr, query_len);
 		}