C++: Fix support for incremental input with \n

Also fix false positive line continuation on blank line

e.g.
"foo \

bar"

Change-Id: Ic6d345a4b578c955411d119b8438c8dc5065c072
Reviewed-by: Erik Verbruggen <erik.verbruggen@digia.com>

src/libs/3rdparty/cplusplus/Lexer.h

@@ -99,6 +99,11 @@ private:
         unsigned _scanAngleStringLiteralTokens: 1;
     };
 
+    struct State {
+        unsigned char _tokenKind : 7;
+        unsigned char _newlineExpected : 1;
+    };
+
     TranslationUnit *_translationUnit;
     Control *_control;
     const char *_firstChar;
@@ -106,7 +111,10 @@ private:
     const char *_lastChar;
     const char *_tokenStart;
     unsigned char _yychar;
-    int _state;
+    union {
+        unsigned char _state;
+        State s;
+    };
     union {
         unsigned _flags;
         Flags f;