Fix minor PythonDocUtil and DoxygenUtility bugs.

vim/scripts/DoxygenUtility/autoload/DoxygenUtility.vim
	-The `@return` section wouldn't be inserted for return types of
	`void *`, when only `void` was meant to be ignored; fix relevant
	code in `s:InsertFunctionComment()`.

vim/scripts/PythonDocUtil/autoload/PythonDocUtil.vim
	-The `Args:` section would be incorrectly inserted when only
	`self` was present in a function prototype's arguments due to
	bad logic flow in `s:InsertFunctionComment()`. Fix.