mcast-snooping: Fix comments format. #264

Job	Run time
dpdk gcc	5s
linux rpm fedora	5m 6s
osx clang --disable-ssl	3m 50s
linux deb no dpdk	6m 22s
linux gcc --disable-ssl	2m 9s
linux clang --disable-ssl	2m 39s
linux gcc c99	2m 18s
linux clang c99	1m 58s
linux gcc test	6m 21s
linux clang test asan	11m 32s
linux clang test ubsan	7m 42s
linux gcc test --enable-shared	9m 19s
linux clang test --enable-shared	8m 58s
linux gcc check check-dpdk dpdk	13m 33s
linux clang check check-dpdk dpdk	13m 14s
linux gcc test -ljemalloc	6m 57s
linux clang test -ljemalloc	7m 15s
linux gcc --enable-afxdp	2m 7s
linux clang --enable-afxdp	2m 30s
linux gcc dpdk --enable-shared	3m 27s
linux clang dpdk --enable-shared	3m 7s
linux gcc dpdk-shared	2m 13s
linux clang dpdk-shared	2m 45s
linux gcc dpdk-shared --enable-shared	4m 5s
linux clang dpdk-shared --enable-shared	3m 2s
linux gcc m32 --disable-ssl	2m 30s
	2h 15m 4s

Provide feedback