Quote targetpath in respack's build event so it works when the path to the...

Quote targetpath in respack's build event so it works when the path to the aegisub checkout has spaces in it

Originally committed to SVN as r4837.

aegisub/tools/common_respack_packresources.vsprops

@@ -6,6 +6,6 @@
 	>
 	<Tool
 		Name="VCPostBuildEventTool"
-		CommandLine="$(TargetPath) &quot;$(ProjectDir)\..\src\libresrc\bitmap.cpp&quot; &quot;$(ProjectDir)\..\src\bitmaps\16&quot; &quot;$(ProjectDir)\..\src\bitmaps\24&quot; &quot;$(ProjectDir)\..\src\bitmaps\misc&quot;&#x0D;&#x0A;$(TargetPath) &quot;$(ProjectDir)\..\src\libresrc\default_config.cpp&quot; &quot;$(ProjectDir)\..\src\libresrc\.\default_mru.json&quot; &quot;$(ProjectDir)\..\src\libresrc\.\default_config.json&quot;"
+		CommandLine="&quot;$(TargetPath)&quot; &quot;$(ProjectDir)\..\src\libresrc\bitmap.cpp&quot; &quot;$(ProjectDir)\..\src\bitmaps\16&quot; &quot;$(ProjectDir)\..\src\bitmaps\24&quot; &quot;$(ProjectDir)\..\src\bitmaps\misc&quot;&#x0D;&#x0A;$(TargetPath) &quot;$(ProjectDir)\..\src\libresrc\default_config.cpp&quot; &quot;$(ProjectDir)\..\src\libresrc\.\default_mru.json&quot; &quot;$(ProjectDir)\..\src\libresrc\.\default_config.json&quot;"
 	/>
 </VisualStudioPropertySheet>