* Makefile.am (maintainer-check): Check for misuses of make,

* Makefile.am (maintainer-check): Check for misuses of make,
autoconf, automake, aclocal, and perl in the testsuite.  Suggest
using $MAKE, $AUTOCONF, $AUTOMAKE, $ACLOCAL, and $PERL instead.
* tests/confsub.test: Use $AUTOCONF and $MAKE.
* tests/extra5.test, tests/extra6.test, tests/lex5.test,
tests/nobase.test, tests/nodist2.test, tests/pr204.test,
tests/pr224.test, tests/pr287.test, tests/strip.test,
tests/yacc8.test: Use $MAKE.