Revert "THRIFT-4982 Remove deprecated C# bindings from the code base"

Only compiler, test, lib and tutorial code.
diff --git a/compiler/cpp/CMakeLists.txt b/compiler/cpp/CMakeLists.txt
index 0675f0e..0d80f79 100644
--- a/compiler/cpp/CMakeLists.txt
+++ b/compiler/cpp/CMakeLists.txt
@@ -76,6 +76,7 @@
 THRIFT_ADD_COMPILER(c_glib  "Enable compiler for C with Glib" ON)
 THRIFT_ADD_COMPILER(cl      "Enable compiler for Common LISP" ON)
 THRIFT_ADD_COMPILER(cpp     "Enable compiler for C++" ON)
+THRIFT_ADD_COMPILER(csharp  "Enable compiler for C#" ON)
 THRIFT_ADD_COMPILER(d       "Enable compiler for D" ON)
 THRIFT_ADD_COMPILER(dart    "Enable compiler for Dart" ON)
 THRIFT_ADD_COMPILER(delphi  "Enable compiler for Delphi" ON)