C++: make CPlusPlus::TranslationUnit::PPLine private.

It's not used otherwise.

Change-Id: I926f5b3d5ea08a5768b61350f2d399eda702aad3
Reviewed-by: hjk <qthjk@ovi.com>

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

@@ -136,7 +136,7 @@ public:
 
     bool maybeSplitGreaterGreaterToken(unsigned tokenIndex);
 
-public:
+private:
     struct PPLine {
         unsigned offset;
         unsigned line;
@@ -158,7 +158,6 @@ public:
         { return offset < other.offset; }
     };
 
-private:
     unsigned findLineNumber(unsigned offset) const;
     unsigned findColumnNumber(unsigned offset, unsigned lineNumber) const;
     PPLine findPreprocessorLine(unsigned offset) const;