Hi.

I made this patch to set an arbitrary value to a global variable.

This patch suffers from the same issue as inline assembly
(https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100380), i.e. it
segfaults if the `rvalue` is created after the global variable.
It seems to be a design issue so I'm not sure what would be the fix for
it and having it fixed would allow me to test this new function much
more and see if things are missing (i.e. it might require a way to
create a constant struct).
See the link above for an explanation of this issue.

Thanks for the review.