* Makefile.am (maintainer-check): Do not require SHELL=/bin/sh

* Makefile.am (maintainer-check): Do not require SHELL=/bin/sh
after $MAKE -e.
* tests/ansi3.test, tests/ansi5.test, tests/cond22.test,
tests/man2.test, tests/subobj3.test, tests/suffix8.test,
tests/suffix11.test: Do not set SHELL=/bin/sh after $MAKE -e.
$SHELL is overridden by tests/defs, so it won't hurt even
if $MAKE -e uses the $SHELL envvar.
* tests/ansi.test, tests/insh2.test, tests/texinfo.test,
tests/texinfo8.test: Use SHELL=$SHELL, not SHELL=/bin/sh.
Reported by Richard Dawe.