perl-IO-Socket-INET6: fix tests, add optional checkdepends.
perl-IO-Socket-INET6: fix tests, add optional checkdepends.

Closes #9414.

necrophcodr/void-packages,kulinacs/void-packages,coredumb/void-packages,NeoChontrix/void-packages,NeoChontrix/void-packages,coredumb/void-packages,NeoChontrix/void-packages,floGik/void-packages,kulinacs/void-packages,coredumb/void-packages,floGik/void-packages,NeoChontrix/void-packages,EaterOfCode/void-packages,kulinacs/void-packages,floGik/void-packages,EaterOfCode/void-packages,EaterOfCode/void-packages,coredumb/void-packages,NeoChontrix/void-packages,necrophcodr/void-packages,kulinacs/void-packages,floGik/void-packages,necrophcodr/void-packages,floGik/void-packages,necrophcodr/void-packages,floGik/void-packages,coredumb/void-packages,kulinacs/void-packages,kulinacs/void-packages,EaterOfCode/void-packages,coredumb/void-packages,NeoChontrix/void-packages,necrophcodr/void-packages,EaterOfCode/void-packages