tools: automake: update to 1.18.1

tools: automake: update to 1.18.1

automake update to 1.18 broke buildbots as we dont have makeinfo host tool
present, after investigation this was an automake regression that was fixed
in 1.18.1[1].

So, since 1.18.1 contains small number of fixes, update to it instead of
just backporting the single commit.

[1] https://cgit.git.savannah.gnu.org/cgit/automake.git/commit/?id=9b92240af4a8f7a3050c13adec367cf48e9ce063

Fixes: d7d02059407b ("tools/automake: update to 1.18")
Signed-off-by: Robert Marko <robimarko@gmail.com>