Silence LeakSanitizer by default in mariabackup, so that phanthom "leaks"

would not hide more interesting information, like invalid memory accesses.


some "leaks" are expected
- partly this is due to weird options parsing, that runs twice, and
does not free memory after the first run.
- also we do not mind to exit()  whenever it makes sense, without full
cleanup.

extra/mariabackup/xtrabackup.cc

@@ -6844,3 +6844,12 @@ int main(int argc, char **argv)
 
 	exit(EXIT_SUCCESS);
 }
+
+
+#if defined (__SANITIZE_ADDRESS__) && defined (__linux__)
+/* Avoid LeakSanitizer's false positives. */
+const char* __asan_default_options()
+{
+  return "detect_leaks=0";
+}
+#endif