Cannot require packages with deprecation warnings from userimg.jl

[tchajed]

I've been trying to get a userimg.jl in Julia v0.4 (master) with PyPlot and Gadfly. These packages both have dependencies that produce warnings at package load time, either due to macro execution or evaluating constants. It seems that when building the sysimg, STDERR is not defined: this results in warnings turning into a rather unexpected UndefVarError(var=:STDERR) at the source of the deprecation warning.

I'm not sure if there's a deeper issue that can be fixed that actually makes STDERR work and outputs the deprecation warnings, but a practical fix is to build the sysimg passing --depwarn=no to julia, which I've confirmed works.