[BUG] <sys/queue.h>: Overlay mode hides glibc definitions

[Alejandro Colomar]

Hello Guillem,

I sent a bug report through gitlab and also through Debian to libbsd a 
few months ago.

When you include <sys/queue.h> with libbsd in overlay mode, libbsd hides 
the definitions for CIRCLEQ_ macros from glibc.

I'd be happy to write the patch, but I have no clue about how libbsd 
works in overlay mode; specifically how you avoid collisions or 
shadowing the system libraries.

If you could give me a basic idea of how you do it, I'll start with the 
code.

Thanks,

Alex.