Fix encoding issue in Ruby when native support not used. Closes GH-1763.

The "backup" to the Ruby native support lib couldn't handle encodings
in the response body that didn't mix with UTF-8 (e.g. UTF-16), which
caused an error and a zero byte response body.

CHANGELOG

@@ -1,6 +1,7 @@
 Release 5.0.27
 --------------
 
+ * Fix encoding issue for Ruby apps that resulted in a 0-byte response body. This occurred when the Ruby native support lib was not used and the app outputted an encoding that doesn't mix with UTF-8 (like UTF-16). Closes GH-1763.
  * Support Debian GNU/kFreeBSD build. Based on contribution by stevenc99.
  * Fix incomplete libuv upgrade: some build files were not autoregenerated during the upgrade from 1.5.0 to 1.8.0 in the previous release.
  * Switch a number of places in the Passenger Core over to using the monotonic clock instead of the wallclock for robustness against clock time-stepping.

src/ruby_supportlib/phusion_passenger/ruby_core_io_enhancements.rb

@@ -61,32 +61,17 @@ def writev3(components, components2, components3)
     end
   else
     def writev(components)
-      return write(components.join(''))
+      return write(components.pack('a*' * components.size))
     end
 
     def writev2(components, components2)
-      data = ''
-      components.each do |component|
-        data << component
-      end
-      components2.each do |component|
-        data << component
-      end
-      return write(data)
+      joined = components + components2
+      return write(joined.pack('a*' * joined.size))
     end
 
     def writev3(components, components2, components3)
-      data = ''
-      components.each do |component|
-        data << component
-      end
-      components2.each do |component|
-        data << component
-      end
-      components3.each do |component|
-        data << component
-      end
-      return write(data)
+      joined = components + components2 + components3
+      return write(joined.pack('a*' * joined.size))
     end
   end