Merge commit c7500ded3 from openzfs git (by Ryan Libby):
FreeBSD libzfs: gcc requires __thread after static Building libzfs with gcc on FreeBSD failed because gcc is picky about the order of keywords in declarations with __thread, whereas clang is more relaxed. https://gcc.gnu.org/onlinedocs/gcc/Thread-Local.html Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Ryan Moeller <ryan@iXsystems.com> Signed-off-by: Ryan Libby <rlibby@FreeBSD.org> Closes #11331