[AST] Revert r346793 and r346781

This somehow breaks the msan bots. Revert while I figure it out.

llvm-svn: 346801
diff --git a/clang/lib/AST/Expr.cpp b/clang/lib/AST/Expr.cpp
index b65ec2c..564484e 100644
--- a/clang/lib/AST/Expr.cpp
+++ b/clang/lib/AST/Expr.cpp
@@ -1174,8 +1174,8 @@
 
 /// getOpcodeStr - Turn an Opcode enum value into the punctuation char it
 /// corresponds to, e.g. "sizeof" or "[pre]++".
-StringRef UnaryOperator::getOpcodeStr(Opcode Opc) {
-  switch (Opc) {
+StringRef UnaryOperator::getOpcodeStr(Opcode Op) {
+  switch (Op) {
 #define UNARY_OPERATION(Name, Spelling) case UO_##Name: return Spelling;
 #include "clang/AST/OperationKinds.def"
   }