MSI: Set correct ruby path after copying files

Althouth the original MSI installer generated by omnbus-td-agent allows
users to choose a folder to install, the installed fluentd command can't
be launched when the user chooses non-default folder since nobody
settles the ruby path embedded in the command.
This patch addresses this issue by running `gem pristine` as a post
install action.

Signed-off-by: Takuro Ashie <ashie@clear-code.com>

td-agent/Rakefile

@@ -314,6 +314,7 @@ class BuildTask
       task :win_batch_files do
         ensure_directory(staging_bindir)
         cp("msi/td-agent-prompt.bat", td_agent_staging_dir)
+        cp("msi/td-agent-post-install.bat", staging_bindir)
         cp("msi/td-agent.bat", staging_bindir)
         cp("msi/td-agent-gem.bat", staging_bindir)
       end

td-agent/msi/source.wxs

@@ -90,5 +90,14 @@
     <WixVariable Id="WixUIInfoIco" Value="assets\icon.ico" />
     <WixVariable Id="WixUINewIco" Value="assets\icon.ico" />
     <WixVariable Id="WixUIUpIco" Value="assets\icon.ico" />
+
+    <!-- Settle paths in executables generated by RubyGems -->
+    <CustomAction Id="PostInstall"
+		  ExeCommand="[PROJECTLOCATION]bin\td-agent-post-install.bat"
+		  Directory="PROJECTLOCATION" Execute="deferred" Return="check"/>
+    <InstallExecuteSequence>
+      <Custom Action="PostInstall" After="InstallFiles">NOT Installed</Custom>
+    </InstallExecuteSequence>
+
   </Product>
 </Wix>

td-agent/msi/td-agent-post-install.bat

@@ -0,0 +1,5 @@
+@echo off
+title Td-agent post install script
+if not "%~dp0" == "C:\opt\td-agent\bin\" (
+   %~dp0gem pristine --only-executables --all
+)