Robert Maynard authored Jan 23, 2017 and Brad King committed Apr 18, 2017

Previously the `TARGET_OBJECTS` generator expression was limited
only to use in a buildsystem context so that Xcode's placeholders
in object file paths can be evaluated.  Lift this restriction so
that the expression can at least be used in most settings.

Co-Author: Brad King <brad.king@kitware.com>