Now that C++17 is official (https://www.iso.org/standard/68564.html), start changing the C++1z terminology over to C++17. NFC intended, these are all mechanical changes.

llvm-svn: 319688
diff --git a/clang/lib/Lex/Lexer.cpp b/clang/lib/Lex/Lexer.cpp
index b069719..3f13bb8 100644
--- a/clang/lib/Lex/Lexer.cpp
+++ b/clang/lib/Lex/Lexer.cpp
@@ -1649,7 +1649,7 @@
     if (!LangOpts.C99) {
       if (!isHexaLiteral(BufferPtr, LangOpts))
         IsHexFloat = false;
-      else if (!getLangOpts().CPlusPlus1z &&
+      else if (!getLangOpts().CPlusPlus17 &&
                std::find(BufferPtr, CurPtr, '_') != CurPtr)
         IsHexFloat = false;
     }
@@ -3178,7 +3178,7 @@
                                ConsumeChar(ConsumeChar(CurPtr, SizeTmp, Result),
                                            SizeTmp2, Result),
                                tok::utf8_string_literal);
-        if (Char2 == '\'' && LangOpts.CPlusPlus1z)
+        if (Char2 == '\'' && LangOpts.CPlusPlus17)
           return LexCharConstant(
               Result, ConsumeChar(ConsumeChar(CurPtr, SizeTmp, Result),
                                   SizeTmp2, Result),