Test case for initctl signal

This commit implements a test for the signal feature of initctl. The
existing service used in tests (`common/service.sh`) has been extended
with a signal trap handler. When SIGUSR1 is received, it will write the
string `'USR1'` to `/tmp/usr1.log`. The test will run `initctl signal
service.sh SIGUSR1` and assert that the contents of the file
`/tmp/usr1.log` really is `USR1`.

test/Makefile.am

@@ -8,6 +8,7 @@ EXTRA_DIST		+= add-remove-dynamic-service-sub-config.sh
 EXTRA_DIST		+= start-stop-service.sh
 EXTRA_DIST		+= start-stop-service-sub-config.sh
 EXTRA_DIST		+= start-kill-service.sh
+EXTRA_DIST		+= signal-service.sh
 
 AM_TESTS_ENVIRONMENT	 = TENV_ROOT='$(abs_builddir)/tenv-root/';
 AM_TESTS_ENVIRONMENT	+= export TENV_ROOT;
@@ -28,6 +29,7 @@ TESTS			+= add-remove-dynamic-service-sub-config.sh
 TESTS			+= start-stop-service.sh
 TESTS			+= start-stop-service-sub-config.sh
 TESTS			+= start-kill-service.sh
+TESTS			+= signal-service.sh
 
 clean-local:
 	-rm -rf $(builddir)/tenv-root/