add missing <optional> include

Mic92 · Mic92 · commit 61b53ce7cfa8 · 2021-11-28T11:26:33.000+01:00
diff --git a/src/patchelf.cc b/src/patchelf.cc
@@ -26,6 +26,7 @@
 #include <string>
 #include <unordered_map>
 #include <vector>
+#include <optional>
 
 #include <cassert>
 #include <cerrno>
