There's a convenient option in recent versions of cmake to set the C standard in a portable way, but this is unavailable in the minimum version of cmake we require (2.6). v000 uses a set of switches based on a subset of compiler ids we're likely to support. The options themselves I pulled from cursory searches; I haven't tested with anything but gcc 4.8.4.
The LCE doesn't compile with ANSI C (-std=c89), but required almost no changes with C99. The only change with -pedantic-errors required some minor tweaks to get_user_info.