https://bugs.webkit.org/show_bug.cgi?id=127097

Reviewed by Anders Carlsson.

* Configurations/PluginService.32.xcconfig: Set SKIP_INSTALL to YES on iOS.
* Configurations/PluginService.64.xcconfig: Ditto.
* Configurations/PluginService.Development.xcconfig: Ditto.
* WebKit2.xcodeproj/project.pbxproj: Modified the "Add XPCServices symlink"
build phase to only execute on OS X. Modified the
"Copy XPC services for engineering builds" build phase to copy files
directly to WebKit2.framework/XPCServices/ on iOS, and modified its
output file paths to omit "Versions/A/" (since OS X will have a
XPCServices symlink at the root of the framework bundle).

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@162146 268f45cc-cd09-0410-ab3c-d52691b4dbfc