Use Register over unsigned in LateEHPrepare (NFC)

Summary:
While D65962 is pending for review, I landed D65475 that added one more
use of `unsigned`. Changed it to `Register`.

Reviewers: dsanders

Subscribers: dschuff, sbc100, jgravelle-google, hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D66064

llvm-svn: 368727

llvm/lib/Target/WebAssembly/WebAssemblyLateEHPrepare.cpp

@@ -340,7 +340,7 @@ bool WebAssemblyLateEHPrepare::addExceptionExtraction(MachineFunction &MF) {
               WebAssembly::ClangCallTerminateFn);
       assert(ClangCallTerminateFn &&
              "There is no __clang_call_terminate() function");
-      unsigned Reg = MRI.createVirtualRegister(&WebAssembly::I32RegClass);
+      Register Reg = MRI.createVirtualRegister(&WebAssembly::I32RegClass);
       BuildMI(ElseMBB, DL, TII.get(WebAssembly::CONST_I32), Reg).addImm(0);
       BuildMI(ElseMBB, DL, TII.get(WebAssembly::CALL_VOID))
           .addGlobalAddress(ClangCallTerminateFn)