Fixes setcookie to only send one Set-Cookie header per name

According to the IETF RFC 6265, only one Set-Cookie header should be sent per cookie name.

Fixes https://bugs.php.net/bug.php?id=67736

Cherry-picks and adapts 208deda (#795) for master
What's wrong with `HashTable`?
Le 28 sept. 2014 07:39, "Xinchen Hui" <notifications@github.com> a écrit :

> In main/SAPI.h:
>
> > @@ -137,6 +137,7 @@ typedef struct _sapi_globals_struct {
> >  	zval callback_func;
> >  	zend_fcall_info_cache fci_cache;
> >  	zend_bool callback_run;
> > +	HashTable *cookies;
>
> maybe a inline struct here is better , HashTable cookies..
>
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> <https://github.com/php/php-src/pull/849/files#r18127729>.
>