OS X: Fix Info.plist placement in a CFBundle

Fix cmOSXBundleGenerator::CreateCFBundle to place Info.plist under the
same root directory as the rest of the bundle.  Without this, Info.plist
was placed into CMAKE_BINARY_DIR, not CMAKE_CURRENT_BINARY_DIR because
the target path was not generated correctly.

Source/cmOSXBundleGenerator.cxx

@@ -178,7 +178,7 @@ void cmOSXBundleGenerator::CreateCFBundle(const std::string& targetName,
 
   // Configure the Info.plist file.  Note that it needs the executable name
   // to be set.
-  std::string plist =
+  std::string plist = root + "/" +
     this->GT->Target->GetCFBundleDirectory(this->ConfigName, true);
   plist += "/Info.plist";
   this->LocalGenerator->GenerateAppleInfoPList(this->GT->Target,