Some <syslog.h> fixes.

This whole file is bogus, but if we're going to have it, we may as well
make an effort. Add LOG_NFACILITIES. Also stop using octal like it's 1970,
and so I can have some confidence that these constants are actually right.

Bug: N/A
Test: built inetutils with a modified standalone toolchain
Change-Id: Ifd6f661f87845bcc5843d68474cb836afb698058