Fix GetUnknownRequestHeader (return null on inexistent header)
Fix GetUnknownRequestHeader (return null on inexistent header)

Signed-off-by: Etienne CHAMPETIER <d24370f93c848f9b9e9043ebb082d433901eaa60@fiducial.net>

gitchomik/HyperFastCgi,gitchomik/HyperFastCgi,xplicit/HyperFastCgi,gitchomik/HyperFastCgi,xplicit/HyperFastCgi,xplicit/HyperFastCgi