patch 8.1.1355: obvious mistakes are accepted as valid expressions

Problem:    Obvious mistakes are accepted as valid expressions.
Solution:   Be more strict about parsing numbers. (Yasuhiro Matsumoto,
            closes #3981)
diff --git a/src/ops.c b/src/ops.c
index 975a56f..a989ce2 100644
--- a/src/ops.c
+++ b/src/ops.c
@@ -5794,7 +5794,7 @@
 		0 + (dobin ? STR2NR_BIN : 0)
 		    + (dooct ? STR2NR_OCT : 0)
 		    + (dohex ? STR2NR_HEX : 0),
-		NULL, &n, maxlen);
+		NULL, &n, maxlen, FALSE);
 
 	/* ignore leading '-' for hex and octal and bin numbers */
 	if (pre && negative)