Add missing include in folly/ExceptionString.cpp

Summary: [Folly] Add missing include in `folly/ExceptionString.cpp`.

Reviewed By: ot, luciang

Differential Revision: D22529764

fbshipit-source-id: 91af74023fd81b1882a19889fd92fda4e1bdfcc7

folly/ExceptionString.cpp

@@ -18,6 +18,8 @@
 
 #include <utility>
 
+#include <folly/lang/Exception.h>
+
 namespace folly {
 
 /**

folly/ExceptionString.h

@@ -19,6 +19,7 @@
 #include <exception>
 #include <string>
 #include <type_traits>
+#include <typeinfo>
 
 #include <folly/Demangle.h>
 #include <folly/FBString.h>