Merge branch 'master' into ng/master

* master:
  tests: remove an obsolete comment
  tests: remove mostly-redundant tests on silent rules

Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>

diff --cc t/silent-c.sh
Simple merge

diff --cc t/silent-cxx.sh
Simple merge

diff --cc t/silent-lt.sh
Simple merge

diff --cc t/silent-many-languages.sh
Simple merge

diff --cc t/silent-yacc.sh
Simple merge