UI: errors in buttons now show in info report

Mistakes in button expressions were previously only printed to the console.

source/blender/python/generic/py_capi_utils.h

@@ -32,6 +32,7 @@ void			PyC_ObSpit(const char *name, PyObject *var);
 void			PyC_LineSpit(void);
 void			PyC_StackSpit(void);
 PyObject *		PyC_ExceptionBuffer(void);
+PyObject *		PyC_ExceptionBuffer_Simple(void);
 PyObject *		PyC_Object_GetAttrStringArgs(PyObject *o, Py_ssize_t n, ...);
 PyObject *		PyC_FrozenSetFromStrings(const char **strings);
 PyObject *		PyC_Err_Format_Prefix(PyObject *exception_type_prefix, const char *format, ...);