ENH: New OutputParser::Process() signature

This overload accepts a null-terminated string instead of requiring a
length.  It is useful to pass some fake process output before and after
the real process output.

Source/cmProcessTools.h

@@ -35,6 +35,8 @@ public:
         in any more data and false if it is done.  */
     bool Process(const char* data, int length)
       { return this->ProcessChunk(data, length); }
+    bool Process(const char* data)
+      { return this->Process(data, static_cast<int>(strlen(data))); }
 
     virtual ~OutputParser() {}
   protected: