portability: fix for BSD make.

Reported by Johan van Selst at
<http://lists.gnu.org/archive/html/bug-bison/2010-03/msg00016.html>.
* tests/local.mk ($(TESTSUITE)): Qualify package.m4 in
this dependency list as in package.m4's target rule.
(cherry picked from commit cf80e9c3868b4a6a9caf53c3b281ee089deffc86)

Conflicts:

	tests/Makefile.am