Ignore failures when setting the default "any" device DLL to LINUX_SLL2.

Ignore failures when setting the default "any" device DLL to LINUX_SLL2.

If the user didn't explicitly request DLT_LINUX_SLL2 with -y, attempt to
set the link-layer type on the "any" device to DLT_LINUX_SLL2, but, if
that fails, just drive on - it could be the Solaris or macOS "any"
device, neither of which support the Linux-style headers, or it could be
a tcpdump built with a newer libpcap but dynamically-linked, and running
on a system with an older libpcap that doesn't support DLT_LINUX_SLL2.

Fixes #1057.

(cherry picked from commit c6b4ee68786c76d47327944e9f3be779bcfe4c6e)