Add DEVELOPER flag, set by default.

This is a bit messier than I'd like, but we want to clearly remove all
dev code (not just have it uncalled), so we remove fields and functions
altogether rather than stub them out.  This means we put #ifdefs in callers
in some places, but at least it's explicit.

We still run tests, but only a subset, and we run with NO_VALGRIND under
Travis to avoid increasing test times too much.

See-also: #176
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

common/debug.c

@@ -50,13 +50,16 @@ static void crashlog_activate(void)
 
 void subdaemon_debug(int argc, char *argv[])
 {
+#if DEVELOPER
 	int i;
 	bool printed = false;
+#endif
 
 	err_set_progname(argv[0]);
 	backtrace_state = backtrace_create_state(argv[0], 0, NULL, NULL);
 	crashlog_activate();
 
+#if DEVELOPER
 	for (i = 1; i < argc; i++) {
 		if (strstarts(argv[i], "--dev-disconnect=")) {
 			dev_disconnect_init(atoi(argv[i]
@@ -73,4 +76,5 @@ void subdaemon_debug(int argc, char *argv[])
 			printed = true;
 		}
 	}
+#endif
 }