Revert "[CodeGenCXX] Treat 'this' as noalias in constructors"

This reverts commit https://reviews.llvm.org/rL344150 which causes
MachineOutliner related failures on the ppc64le multistage buildbot.

llvm-svn: 344526
diff --git a/clang/test/CodeGenCXX/amdgcn-automatic-variable.cpp b/clang/test/CodeGenCXX/amdgcn-automatic-variable.cpp
index c5cc881..9830a78 100644
--- a/clang/test/CodeGenCXX/amdgcn-automatic-variable.cpp
+++ b/clang/test/CodeGenCXX/amdgcn-automatic-variable.cpp
@@ -67,7 +67,7 @@
 void func3() {
   // CHECK: %[[a:.*]] = alloca %class.A, align 4, addrspace(5)
   // CHECK: %[[r0:.*]] = addrspacecast %class.A addrspace(5)* %[[a]] to %class.A*
-  // CHECK: call void @_ZN1AC1Ev(%class.A* noalias %[[r0]])
+  // CHECK: call void @_ZN1AC1Ev(%class.A* %[[r0]])
   // CHECK: call void @_ZN1AD1Ev(%class.A* %[[r0]])
   A a;
 }