Always build tests

There are no dependencies or requirements there that we don't already
need for weston itself.  So lets just always build them.

Use check_PROGRAMS for the matrix unit test case.

configure.ac

@@ -179,12 +179,6 @@ AC_ARG_ENABLE(tablet-shell, [  --enable-tablet-shell],,
 AM_CONDITIONAL(ENABLE_TABLET_SHELL,
 	       test x$enable_tablet_shell = xyes)
 
-AC_ARG_ENABLE(tests,
-	      AS_HELP_STRING([--disable-tests],
-			     [do not build unit tests [default=enabled]]),,
-	      enable_tests=yes)
-AM_CONDITIONAL(BUILD_TESTS, test x$enable_tests = xyes)
-
 if test "x$GCC" = "xyes"; then
 	GCC_CFLAGS="-Wall -Wextra -Wstrict-prototypes -Wmissing-prototypes \
 		-Wno-unused-parameter -Wno-missing-field-initializers \

tests/Makefile.am

@@ -1,9 +1,8 @@
-if BUILD_TESTS
+TESTS = $(check_PROGRAMS)
 
-noinst_PROGRAMS = matrix-test setbacklight
-
-endif
+check_PROGRAMS = matrix-test
 
+noinst_PROGRAMS = setbacklight
 
 AM_CFLAGS = $(GCC_CFLAGS)
 AM_CPPFLAGS = -I$(top_srcdir)/src -DUNIT_TEST $(COMPOSITOR_CFLAGS)