sysd_monitor: Monitor and log errors

Note some aspects of the code are non-optimal to allow better unit
testing.

Tested:
- Verified failure detected and correct error created in qemu

Change-Id: I1d4c9638fc13147508168278cc5ab90c37e1fb8e
Signed-off-by: Andrew Geissler <geissonator@yahoo.com>
diff --git a/test/Makefile.am.include b/test/Makefile.am.include
index 95bf636..ba8d106 100644
--- a/test/Makefile.am.include
+++ b/test/Makefile.am.include
@@ -1,4 +1,8 @@
 test_systemd_parser_SOURCES = %reldir%/systemd_parser.cpp systemd_target_parser.cpp
+test_systemd_signal_SOURCES = %reldir%/systemd_signal.cpp systemd_target_signal.cpp
 
 check_PROGRAMS += \
 	%reldir%/systemd_parser
+
+check_PROGRAMS += \
+	%reldir%/systemd_signal