Added some missing jruby files to the Makefile

Makefile.am

@@ -1115,13 +1115,15 @@ ruby_EXTRA_DIST=                                                             \
   ruby/src/main/java/com/google/protobuf/jruby/RubyBuilder.java              \
   ruby/src/main/java/com/google/protobuf/jruby/RubyDescriptor.java           \
   ruby/src/main/java/com/google/protobuf/jruby/RubyDescriptorPool.java       \
+  ruby/src/main/java/com/google/protobuf/jruby/RubyEnum.java                 \
   ruby/src/main/java/com/google/protobuf/jruby/RubyEnumBuilderContext.java   \
   ruby/src/main/java/com/google/protobuf/jruby/RubyEnumDescriptor.java       \
-  ruby/src/main/java/com/google/protobuf/jruby/RubyEnum.java                 \
   ruby/src/main/java/com/google/protobuf/jruby/RubyFieldDescriptor.java      \
+  ruby/src/main/java/com/google/protobuf/jruby/RubyFileBuilderContext.java   \
+  ruby/src/main/java/com/google/protobuf/jruby/RubyFileDescriptor.java       \
   ruby/src/main/java/com/google/protobuf/jruby/RubyMap.java                  \
-  ruby/src/main/java/com/google/protobuf/jruby/RubyMessageBuilderContext.java \
   ruby/src/main/java/com/google/protobuf/jruby/RubyMessage.java              \
+  ruby/src/main/java/com/google/protobuf/jruby/RubyMessageBuilderContext.java \
   ruby/src/main/java/com/google/protobuf/jruby/RubyOneofBuilderContext.java  \
   ruby/src/main/java/com/google/protobuf/jruby/RubyOneofDescriptor.java      \
   ruby/src/main/java/com/google/protobuf/jruby/RubyProtobuf.java             \