Include targets of preference edges in all_interf_regs.  Not needed for correctness, but this way temporaries that have preferences but no interferences do not fall in the default case of Coloring.alloc_of_coloring.  This used to create uncoalesced moves esp. on Arm.


git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@1299 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e