C++1y is now C++14!

Changes diagnostic options, language standard options, diagnostic identifiers, diagnostic wording to use c++14 instead of c++1y. It also modifies related test cases to use the updated diagnostic wording.

llvm-svn: 215982
diff --git a/clang/test/SemaCXX/cxx1y-constexpr-not-const.cpp b/clang/test/SemaCXX/cxx1y-constexpr-not-const.cpp
index 3f100b8..071b39c 100644
--- a/clang/test/SemaCXX/cxx1y-constexpr-not-const.cpp
+++ b/clang/test/SemaCXX/cxx1y-constexpr-not-const.cpp
@@ -14,5 +14,5 @@
 // expected-error@6 {{non-constexpr declaration of 'f' follows constexpr declaration}}
 // expected-note@5 {{previous}}
 #else
-// expected-warning@5 {{'constexpr' non-static member function will not be implicitly 'const' in C++1y; add 'const' to avoid a change in behavior}}
+// expected-warning@5 {{'constexpr' non-static member function will not be implicitly 'const' in C++14; add 'const' to avoid a change in behavior}}
 #endif