Add missing includes for msvc

Summary: MSVC is a stricter compiler and needs additional includes explicitly declared

Test Plan: fbmake runtests

Reviewed By: njormrod@fb.com

FB internal diff: D1277004

folly/FBString.h

@@ -61,6 +61,7 @@
 #include <atomic>
 #include <limits>
 #include <type_traits>
+#include <algorithm>
 
 // libc++ doesn't provide this header
 #ifndef _LIBCPP_VERSION

folly/Optional.h

@@ -61,6 +61,7 @@
 
 #include <boost/operators.hpp>
 
+#include "folly/Portability.h"
 
 namespace folly {
 

folly/String.cpp

@@ -22,6 +22,7 @@
 #include <cstring>
 #include <stdexcept>
 #include <iterator>
+#include <cctype>
 #include <glog/logging.h>
 
 namespace folly {

folly/Traits.h

@@ -22,6 +22,7 @@
 #include <memory>
 #include <limits>
 #include <type_traits>
+#include <functional>
 
 #include "folly/Portability.h"
 

folly/wangle/Future.h

@@ -21,6 +21,7 @@
 #include <functional>
 #include <memory>
 #include <type_traits>
+#include <vector>
 
 #include "folly/MoveWrapper.h"
 #include "Promise.h"