Avoid redundant compilation when the tests are disabled

test/Makefile.am

@@ -2,17 +2,16 @@
 #
 # SPDX-License-Identifier: BSD-3-Clause
 #
-EXTRA_LTLIBRARIES = libmtime_check.la
 check_PROGRAMS = test_runner
 TESTS = test_runner test_python.sh
 TEST_EXTENSIONS = .sh
 
-AM_CPPFLAGS = -I$(top_srcdir)/include
-
 if ENABLE_CHECK
+check_LTLIBRARIES = libmtime_check.la
+
+AM_CPPFLAGS = -I$(top_srcdir)/include
 AM_CFLAGS = $(CHECK_CFLAGS)
 test_runner_LDADD = libmtime_check.la $(top_builddir)/src/libmtime.la $(CHECK_CLIBS)
-endif ENABLE_CHECK
 
 libmtime_check_la_SOURCES = \
     mtime_calendar_test.c   \
@@ -27,9 +26,7 @@ libmtime_check_la_SOURCES = \
     mtime_time_test.h       \
     mtime_timedelta_test.c  \
     mtime_timedelta_test.h
+endif ENABLE_CHECK
 
 clean-local:
 	rm -rf *.dSYM
-
-MOSTLYCLEANFILES = $(EXTRA_LTLIBRARIES)
-