quagga: Remove iflist global variable

quagga: Remove iflist global variable

The file if.c has a iflist that had the list of interfaces
in the default vrf.  Remove this variable and replace
with a vrf_iflist lookup on the default vrf where it
was used.

Additionally, modify ptm code to iterate over all vrf's
when enabling ptm.

Ticket: CM-10338
Signed-off-by: Donald Sharp <sharpd@cumulusnetworks.com>
Reviewed-by: Don Slice <dslice@cumulusnetworks.com>
Reviewed-by: Radhika Mahankali <radhika@cumulusnetworks.com>