refactor: move func_sort_ver from bootstrap.in to funclib.sh.

* gl/build-aux/bootstrap.in (func_sort_ver): Move from here...
* gl/build-aux/funclib.sh (func_sort_ver): ...to here.
* bootstrap: Regenerate.

Signed-off-by: Gary V. Vaughan <gary@gnu.org>
gnulib: use func_sort_ver instead of GNU sort -V in do-release-commit-and-tag.

* gl/build-aux/do-release-commit-and-tag: Source funclib.sh and
then use portable func_sort_ver rather than force installation of
all GNU coreutils just for sort -V support.

Signed-off-by: Gary V. Vaughan <gary@gnu.org>