Projucer: Leave absolute paths alone when adding project items to Xcode project

extras/Projucer/Source/ProjectSaving/jucer_ProjectExport_Xcode.h

@@ -3129,7 +3129,7 @@ private:
             auto itemPath = projectItem.getFilePath();
             build_tools::RelativePath path;
 
-            if (itemPath.startsWith ("${"))
+            if (itemPath.startsWith ("${") || build_tools::isAbsolutePath (itemPath))
                 path = build_tools::RelativePath (itemPath, build_tools::RelativePath::unknown);
             else
                 path = build_tools::RelativePath (projectItem.getFile(), getTargetFolder(), build_tools::RelativePath::buildTargetFolder);