maint: fix a syntax-check violation from commit 12641bd.

* build-aux/ltmain.in (func_mode_link): Reverse test operands to
forestall misinterpretation of contests of shell variable as
operand 1.

Signed-off-by: Gary V. Vaughan <gary@gnu.org>
maint: bump serials on m4 sources changed since v2.4.2.

* m4/argz.m4: Bump serial to 6.
* m4/libtool.m4: Bump serial to 58.
* m4/ltdl.m4: Bump serial to 19.
* m4/ltoptions.m4: Bump serial to 8.

Signed-off-by: Gary V. Vaughan <gary@gnu.org>
maint: Update README-release for Makefile.inc -> ltdl.mk rename.

* gl/top/README-release.diff: s/Makefile.inc/ltdl.mk/g

Signed-off-by: Gary V. Vaughan <gary@gnu.org>
libltdl: bump -version-info revision by 1.

The only changes to libltdl sources since v2.4.2 have been
cosmetic and stylistic.
* libltdl/ltdl.mk (LTDL_VERSION_INFO): For a release with no
interface changes C:R:A becomes C:R+1:A.

Signed-off-by: Gary V. Vaughan <gary@gnu.org>
tests: use K&R main() syntax for old-ltdl-iface.at.

At least Mac OS 10.8.5 clang chokes on the previous
'const void *argv[]' parameter, but since we don't use it
anyway, keep to the theme of old api support and use K&R
syntax.
* tests/old-ltdl-iface.at (old.c): Use 'main ()' instead of
unportable 'int main (int argc, const void *argv[])'.

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