bug#55657: libgccjit is unusable

[John Kehayias]

Thanks for the new patchset Lily, very excited to have emacs with native 
compiliation in upstream Guix! (At the very least so I don't have to compile 
libgccjit and emacs)

For everyone following along at home, please see 
https://issues.guix.gnu.org/57086

As for the original issue here, I guess the LIBRARY_PATH and ld shadowing is 
the workaround. I don't know if that is something that can/should be 
incorporated into the libgccjit package definition or should just be handled by 
any package using it. Currently, that will just be emacs anyway and hopefully 
the discussion here is useful to anyone trying to use libgccjit.

Thanks again Lily and Andrew for your work here!