Add ASAN options into systemd service files

By default ASAN only reports the errors and doesn't cause the program to
crash. By forcing a SIGABRT, the process will generate a core dump which
causes the test to fail.

Although the act of placing environment variables inside the systemd
service file might seem intrusive, they have no effect on non-ASAN
builds. This appears to be the most convenient and straightforward way of
changing ASAN behavior for testing.

etc/maxscale.service.in

@@ -21,5 +21,8 @@ TimeoutStartSec=120
 LimitNOFILE=65535
 StartLimitBurst=0
 
+# Only relevant when MaxScale is linked with -fsanitize=address
+Environment=ASAN_OPTIONS=abort_on_error=1
+
 [Install]
 WantedBy=multi-user.target