formula: b* is siSERE

Since b[+] and [*0] are siSERE, b* is siSERE as well.
Suggested by Victor Khomenko.

* spot/tl/formula.cc: Implement that for Star and also
in the concatenation rule.
* tests/core/kind.test, tests/core/ltlfilt.test: Adjust.
14 jobs for next in 180 minutes and 39 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Build
passed #42359
alpine-gcc

00:40:37

passed #42410
arch-clang

00:48:14

passed #42361
arch-gcc-glibcxxdebug

00:46:50

passed #42358
debian-gcc-snapshot

01:59:46

passed #42356
debian-stable-gcc

00:37:58

passed #42357
debian-unstable-gcc-coverage

00:38:18

88.6%
passed #42364
debpkg-stable

02:10:02

passed #42365
debpkg-unstable

02:04:26

passed #42362
mingw-shared

00:09:46

passed #42363
mingw-static

00:07:45

passed #42366
rpm-pkg

00:40:15

failed #42360
arch-clang

00:43:01

 
  Publish
passed #42367
dput
publish-rpm

00:00:28

passed #42368
dput
publish-unstable

00:02:20