How to cross-compile to ARM and generate a static binary?

[mildred]

I need to write a small utility that will run on a BeagleBone Black with glibc 
2.26 (I have glibc 2.28 on my dev machine). So I need to find both a toolchain 
cross-compiler and a way to avoid linking to latest glibc symbols. I could find 
a COPR repository for fedora with the toolchain.

To link with older symbols, I found the solution on 
[https://stackoverflow.com/a/61327520/6020072](https://stackoverflow.com/a/61327520/6020072).
 basically, I create a file symver.h with:
    
    
    __asm__(".symver fcntl,fcntl@GLIBC_2.4");
    
    
    Run

And I then build with: `nim c --cpu:arm --os:linux --passC:--include=symver.h` 
(`--include` ensures that the `.symver` directive comes very early in linking 
process)

it was quite hard to come to this, so I wanted to share it.

Also, for some reason, I had to clean up `~/.cache/nim` to get the build pass.