GlobalISel: convert buildSequence to use non-deprecated instructions.

G_SEQUENCE is going away soon so as a first step the MachineIRBuilder needs to
be taught how to emulate it with alternatives. We use G_MERGE_VALUES where
possible, and a sequence of G_INSERTs if not.

llvm-svn: 306119
diff --git a/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp b/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp
index 7fefbf9..239bad2 100644
--- a/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp
@@ -582,7 +582,7 @@
     MIB.addUse(Zero);
   }
 
-  MIRBuilder.buildSequence(getOrCreateVReg(CI), Res, 0, Overflow, Width);
+  MIRBuilder.buildSequence(getOrCreateVReg(CI), {Res, Overflow}, {0, Width});
   return true;
 }