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

Only compiler, test, lib and tutorial code.
diff --git a/compiler/cpp/Makefile.am b/compiler/cpp/Makefile.am
index 05c9121..2f962fe 100644
--- a/compiler/cpp/Makefile.am
+++ b/compiler/cpp/Makefile.am
@@ -73,6 +73,7 @@
                   src/thrift/generate/t_c_glib_generator.cc \
                   src/thrift/generate/t_cl_generator.cc \
                   src/thrift/generate/t_cpp_generator.cc \
+                  src/thrift/generate/t_csharp_generator.cc \
                   src/thrift/generate/t_d_generator.cc \
                   src/thrift/generate/t_dart_generator.cc \
                   src/thrift/generate/t_delphi_generator.cc \