It refuses to compile citing that. Obviously I could set that to fix it, but why should I have to? Why isn't it using the portage default? I can't post --info at the minute (another machine), but it doesn't contain the requested variable. I should point out i'm on a hardened system, don't know if it's got anything to do with it. LibOl is a dependency of syslog-ng, so i'm filing this as blocker with P1. Metalog does not require it, if you were wondering.
Confirmed on hardened-sources too, which leads me to believe it's a hardened bug, refiling under that. At suggestion of someone else, i'm toning down the severity and priority
Reopen with actual errors and emerge --info.