RTTI: refactor the uniqueness question into CGCXXABI.

This also brings the code into closer conformance with usual LLVM
coding style and other surrounding conventions.

llvm-svn: 205158
diff --git a/clang/lib/CodeGen/ItaniumCXXABI.cpp b/clang/lib/CodeGen/ItaniumCXXABI.cpp
index 1648c3b..27825ab 100644
--- a/clang/lib/CodeGen/ItaniumCXXABI.cpp
+++ b/clang/lib/CodeGen/ItaniumCXXABI.cpp
@@ -248,6 +248,9 @@
 class iOS64CXXABI : public ARMCXXABI {
 public:
   iOS64CXXABI(CodeGen::CodeGenModule &CGM) : ARMCXXABI(CGM) {}
+
+  // ARM64 libraries are prepared for non-unique RTTI.
+  bool shouldRTTIBeUnique() override { return false; }
 };
 }