Re-enable "[MachineCopyPropagation] Extend pass to do COPY source forwarding"

Re-enable commit r323991 now that r325931 has been committed to make
MachineOperand::isRenamable() check more conservative w.r.t. code
changes and opt-in on a per-target basis.

llvm-svn: 326208
diff --git a/llvm/test/CodeGen/Mips/llvm-ir/sub.ll b/llvm/test/CodeGen/Mips/llvm-ir/sub.ll
index d06170f..d839a6e 100644
--- a/llvm/test/CodeGen/Mips/llvm-ir/sub.ll
+++ b/llvm/test/CodeGen/Mips/llvm-ir/sub.ll
@@ -163,7 +163,7 @@
 ; MMR3: subu16   $5, $[[T19]], $[[T20]]
 
 ; MMR6: move     $[[T0:[0-9]+]], $7
-; MMR6: sw       $[[T0]], 8($sp)
+; MMR6: sw       $7, 8($sp)
 ; MMR6: move     $[[T1:[0-9]+]], $5
 ; MMR6: sw       $4, 12($sp)
 ; MMR6: lw       $[[T2:[0-9]+]], 48($sp)