Utils: Add mapping for uniqued MDLocations

Still doesn't handle distinct ones.  Part of PR21433.

llvm-svn: 225914
diff --git a/llvm/test/Linker/Inputs/mdlocation.ll b/llvm/test/Linker/Inputs/mdlocation.ll
new file mode 100644
index 0000000..b01b459
--- /dev/null
+++ b/llvm/test/Linker/Inputs/mdlocation.ll
@@ -0,0 +1,10 @@
+!named = !{!0, !1, !2, !3, !4, !5, !6, !7}
+
+!0 = !{} ; Use this as a scope.
+!1 = !MDLocation(line: 3, column: 7, scope: !0)
+!2 = !MDLocation(line: 3, column: 7, scope: !0, inlinedAt: !1)
+!3 = !MDLocation(line: 3, column: 7, scope: !0, inlinedAt: !2)
+!4 = distinct !{} ; Test actual remapping.
+!5 = !MDLocation(line: 3, column: 7, scope: !4)
+!6 = !MDLocation(line: 3, column: 7, scope: !4, inlinedAt: !5)
+!7 = !MDLocation(line: 3, column: 7, scope: !4, inlinedAt: !6)