PATCH: remove a CPP warning within comment

[John Marshall]

>>    // Lots of spaces after the backslash: \
>>    foo ();  // Hey!  foo never got called!
> 
> There's a different warning for that - this warning is just for the
> spaces.

They're sort of orthogonal: the spaces one is warning about a portability
(to other compilers) issue, while the multi-line one is a style issue.

I guess what I really meant was

	// Using some other compiler...

	// Lots of spaces after the backslash: \   
	foo ();  // Hey!  foo did get called!
	         // I thought I commented it out in an obfuscated way!

But since the multi-line warning can't be switched off, Sylvain's patch
just changes two warnings into one, which is a good thing.  I hadn't looked
at the multi-line one, and now I understand why skip_line_comment has a
return code :-) -- thanks,

    John