- odd condition/test in PF lexer

(and other lexers too)
This commit rectifies earlier change:
in the lex... even inside quotes, a \ followed by space or tab should
expand to space or tab, and a \ followed by newline should be ignored
(as a line continuation).  compatible with the needs of hoststated
(which has the most strict quoted string requirements), and ifstated
(where one commonly does line continuations in strings).
OK deraadt@, OK millert@

src/usr.sbin/ntpd/parse.y

@@ -1,4 +1,4 @@
-/*	$OpenBSD: parse.y,v 1.69 2018/07/09 12:05:11 krw Exp $ */
+/*	$OpenBSD: parse.y,v 1.70 2018/11/01 00:18:44 sashan Exp $ */
 
 /*
  * Copyright (c) 2002, 2003, 2004 Henning Brauer <henning@openbsd.org>
@@ -635,7 +635,8 @@ yylex(void)
 			} else if (c == '\\') {
 				if ((next = lgetc(quotec)) == EOF)
 					return (0);
-				if (next == quotec || c == ' ' || c == '\t')
+				if (next == quotec || next == ' ' ||
+				    next == '\t')
 					c = next;
 				else if (next == '\n') {
 					file->lineno++;