Add SKIP_LTESTS for skipping specific tests.

regress/Makefile

@@ -210,8 +210,16 @@ t12: $(OBJ)/t12.out
 t-exec:	${LTESTS:=.sh}
 	@if [ "x$?" = "x" ]; then exit 0; fi; \
 	for TEST in ""$?; do \
+		skip=no; \
+		for t in ""$${SKIP_LTESTS}; do \
+			if [ "x$${t}.sh" = "x$${TEST}" ]; then skip=yes; fi; \
+		done; \
+		if [ "x$${skip}" = "xno" ]; then \
 			echo "run test $${TEST}" ... 1>&2; \
 			(env SUDO="${SUDO}" TEST_ENV=${TEST_ENV} ${TEST_SHELL} ${.CURDIR}/test-exec.sh ${.OBJDIR} ${.CURDIR}/$${TEST}) || exit $$?; \
+		else \
+			echo skip test $${TEST} 1>&2; \
+		fi; \
 	done
 
 t-exec-interop:	${INTEROP_TESTS:=.sh}

regress/README.regress

@@ -25,6 +25,7 @@ SUDO: path to sudo/doas command, if desired. Note that some systems
 	(notably systems using PAM) require sudo to execute some tests.
 LTESTS: Whitespace separated list of tests (filenames without the .sh
 	extension) to run.
+SKIP_LTESTS: Whitespace separated list of tests to skip.
 OBJ: used by test scripts to access build dir.
 TEST_SHELL: shell used for running the test scripts.
 TEST_SSH_FAIL_FATAL: set to "yes" to make any failure abort the test