py3.7 fix

PyUnicode_AsUTF8() returns const char* in py3.7 instead of char*. Making
changes to reflect that which should also be safe in
other Python versions.

src/Mod/Part/App/TopologyPy.cpp

@@ -190,7 +190,7 @@ TopoShapePyOld::~TopoShapePyOld()						// Everything handled in parent
 //--------------------------------------------------------------------------
 // TopoShapePyOld Attributes
 //--------------------------------------------------------------------------
-PyObject *TopoShapePyOld::_getattr(char *attr)				// __getattr__ function: note only need to handle new state
+PyObject *TopoShapePyOld::_getattr(const char *attr)				// __getattr__ function: note only need to handle new state
 { 
 	try{
 		// Access the number of attributes at this label
@@ -205,7 +205,7 @@ PyObject *TopoShapePyOld::_getattr(char *attr)				// __getattr__ function: note
 	}
 } 
 
-int TopoShapePyOld::_setattr(char *attr, PyObject *value) 	// __setattr__ function: note only need to handle new state
+int TopoShapePyOld::_setattr(const char *attr, PyObject *value) 	// __setattr__ function: note only need to handle new state
 { 
 	if (Base::streq(attr, "Real"))						// settable new state
 		; 
@@ -712,4 +712,4 @@ PyObject *TopoShapePyOld::exportSTL(PyObject *args)
   Py_Return; 
 }
 
-#endif
+#endif

src/Mod/Part/App/TopologyPy.h

@@ -72,9 +72,9 @@ public:
 	//---------------------------------------------------------------------
 
 	virtual PyObject *_repr(void);  				// the representation
-	PyObject *_getattr(char *attr);				// __getattr__ function
+	PyObject *_getattr(const char *attr);				// __getattr__ function
 	// getter setter
-	int _setattr(char *attr, PyObject *value);	// __setattr__ function
+	int _setattr(const char *attr, PyObject *value);	// __setattr__ function
 
 	// methods
 	PYFUNCDEF_D (TopoShapePyOld,hasChild);