[test] Fix stdlib/RuntimeObjC.swift with newer deployment target
This test stops working with deployment targets that no longer link
@rpath/libswiftCoreGraphics.dylib when running on OSes that still
require the CoreGraphics overlay. Explicitly link it to workaround.
rdar://135451615
(cherry picked from commit a2ee20d490b17cce8465bb5fd71337cf03cdcb26)
(cherry picked from commit d017a852136ed61f25a3916523b3f71ef6364d0e)
