Ideally, you should not use any non-async-signal-safe functions after `fork()`, because the situation after fork is very similar to the situation in the signal handler. In kcrash, we are in signal handler before `fork`, so we shouldn't use `setenv` even before fork. This patch however emulates `setenv` using static memory so should be safe.
Depends on D29809
Signed-off-by: Jiří Paleček <jpalecek@web.de>