CLEANUP: dev/flags: remove useless test in the stdin number parser

The test on "if (err)" after parsing a number was meant to be
"if (*err)" but in practise it will always be true since we at least
have a '\n' there, so no need for testing before writing zero.
This fixes issue #1211.
diff --git a/dev/flags/flags.c b/dev/flags/flags.c
index 669bd09..ccd2205 100644
--- a/dev/flags/flags.c
+++ b/dev/flags/flags.c
@@ -441,8 +441,7 @@
 			while (*err == '-' || *err == '+' ||
 			       (isalnum((unsigned char)*err) && toupper((unsigned char)*err) != 'U' && toupper((unsigned char)*err) != 'L'))
 				err++;
-			if (err)
-				*err = 0;
+			*err = 0;
 		} else {
 			value = argv[0];
 			argv++; argc--;