lib: cpp: thrift: include functional in TServerFramework

Use of `std::placeholders::_1` requires `<functional>`.

Signed-off-by: Chris Friedt <cfriedt@fb.com>
diff --git a/lib/cpp/src/thrift/server/TServerFramework.cpp b/lib/cpp/src/thrift/server/TServerFramework.cpp
index 302cbf1..2431bc2 100644
--- a/lib/cpp/src/thrift/server/TServerFramework.cpp
+++ b/lib/cpp/src/thrift/server/TServerFramework.cpp
@@ -18,6 +18,7 @@
  */
 
 #include <algorithm>
+#include <functional>
 #include <stdexcept>
 #include <stdint.h>
 #include <thrift/server/TServerFramework.h>