Use vsnprintf(3) in syslog(3).

It seemed like a clever trick to use the internal log message formatting
code in syslog(3), but on reflection that means you can't (for example)
format floating point numbers. This patch switches us over to using good
old vsnprintf(3), even though that requires us to jump through a few hoops.

There's no obvious way to unit test this, so I wrote a little program and
ran that.

Bug: 14292866
Change-Id: I9c83500ba9cbb209b6f496067a91bf69434eeef5
3 files changed