[BUGFIX] Properly detect HHVM with fastcgi

Extend the PHP_SAPI check with "srv" to match the interface between
the webserver and PHP also for Facebook's HHVM and set the paths
correctly for HHVM hostings.

Resolves: #57785
Releases: 6.2
Change-Id: Ie9e302f9ce606158f5e70af1930eda778a8a5a34
Reviewed-on: https://review.typo3.org/29335
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn
Reviewed-by: Stefan Neufeind
Tested-by: Stefan Neufeind