forgot to include header files into automake template

src/Makefile.am

@@ -291,20 +291,34 @@ libprotoc_la_SOURCES =                                         \
   google/protobuf/compiler/python/python_generator.cc          \
   google/protobuf/compiler/ruby/ruby_generator.cc              \
   google/protobuf/compiler/csharp/csharp_enum.cc               \
+  google/protobuf/compiler/csharp/csharp_enum.h                \
   google/protobuf/compiler/csharp/csharp_enum_field.cc         \
+  google/protobuf/compiler/csharp/csharp_enum_field.h          \
   google/protobuf/compiler/csharp/csharp_extension.cc          \
+  google/protobuf/compiler/csharp/csharp_extension.h           \
   google/protobuf/compiler/csharp/csharp_field_base.cc         \
+  google/protobuf/compiler/csharp/csharp_field_base.h          \
   google/protobuf/compiler/csharp/csharp_generator.cc          \
   google/protobuf/compiler/csharp/csharp_helpers.cc            \
+  google/protobuf/compiler/csharp/csharp_helpers.h             \
   google/protobuf/compiler/csharp/csharp_message.cc            \
+  google/protobuf/compiler/csharp/csharp_message.h             \
   google/protobuf/compiler/csharp/csharp_message_field.cc      \
+  google/protobuf/compiler/csharp/csharp_message_field.h       \
   google/protobuf/compiler/csharp/csharp_primitive_field.cc    \
+  google/protobuf/compiler/csharp/csharp_primitive_field.h     \
   google/protobuf/compiler/csharp/csharp_repeated_enum_field.cc \
+  google/protobuf/compiler/csharp/csharp_repeated_enum_field.h \
   google/protobuf/compiler/csharp/csharp_repeated_message_field.cc \
+  google/protobuf/compiler/csharp/csharp_repeated_message_field.h \
   google/protobuf/compiler/csharp/csharp_repeated_primitive_field.cc \
+  google/protobuf/compiler/csharp/csharp_repeated_primitive_field.h \
   google/protobuf/compiler/csharp/csharp_source_generator_base.cc \
+  google/protobuf/compiler/csharp/csharp_source_generator_base.h \
   google/protobuf/compiler/csharp/csharp_umbrella_class.cc     \
-  google/protobuf/compiler/csharp/csharp_writer.cc
+  google/protobuf/compiler/csharp/csharp_umbrella_class.h      \
+  google/protobuf/compiler/csharp/csharp_writer.cc             \
+  google/protobuf/compiler/csharp/csharp_writer.h
 
 bin_PROGRAMS = protoc
 protoc_LDADD = $(PTHREAD_LIBS) libprotobuf.la libprotoc.la