Makefile.am:
TESTS += test-argp test-argp-2.sh
-check_PROGRAMS += test-argp
-test_argp_LDADD = @LIBINTL@ $(LDADD)
-EXTRA_DIST += test-argp-2.sh
+TESTS_ENVIRONMENT += EXEEXT='@EXEEXT@'
+check_PROGRAMS += test-argp
+test_argp_LDADD = $(LDADD) @LIBINTL@