If PKG_CONFIG is already overriden then default PKG_CONFIG_ALLOW_CROSS to yes

[infinity0]

I've been trying to cross-compile cargo and although I've succeeded now, I ran into several cases where I had to set random environment variables for it to work. Here, PKG_CONFIG_ALLOW_CROSS seems a bit unnecessary, if PKG_CONFIG is already overriden then probably the user/builder knows what they're doing and there is no need to put artificial guards in that make the process Just Not Work.

[infinity0]

For reference, on Debian the cross-compiling pkg-config programs are called $(host-triplet)-pkg-config and they are just a simple wrapper around pkg-config.

This issue is more about the whole Rust ecosystem rather than this particular package, I'd rather not have to set 20 similar random environment variables in the future across various different crates.

[alexcrichton]

Seems reasonable to me!

[lightern]

Hi, maybe a stupid question, but how should I use PKG_CONFIG_ALLOW_CROSS variable? I've been trying to find the answer for this everywhere.