Unbreak stable/10 buildworlds on arm/arm, mips/mips, mips/mips64, mips/mipsel,
mips/mipsn32, powerpc/powerpc, powerpc/powerpc64, sparc64/sparc64 with gcc
after r293307 (some of the BURN_BRIDGES code)

MFC after: 3 days
Pointyhat to: markj
Sponsored by: EMC / Isilon Storage Division

MFC r279017:

r279017 (by glebius):

Burn bridges to FreeBSD 7.x IGMP stats.