fparseln(3): Update from NetBSD sources.

-fix a condition so that fparseln() doesn't report spurious empty lines
 eg after 2 comment lines, or on EOF after a single comment line
-no escape character means no escaped characters

modify the previous fix so that no pointless realloc()s are done in
the case of multiple empty continuation lines, and comment the code
to make the logics obvious

fparseln is now part of libc in NetBSD so this changes the previous
revision numbering.

Obtained from:	NetBSD (CVS Rev. 1.6-1.7)
MFC after:	2 weeks

lib/libutil/fparseln.c

@@ -1,4 +1,4 @@
-/*	$NetBSD: fparseln.c,v 1.9 1999/09/20 04:48:06 lukem Exp $	*/
+/*	$NetBSD: fparseln.c,v 1.7 2007/03/08 19:57:53 drochner Exp $	*/
 
 /*
  * Copyright (c) 1997 Christos Zoulas.  All rights reserved.
@@ -59,7 +59,7 @@ isescaped(const char *sp, const char *p, int esc)
 
 	/* No escape character */
 	if (esc == '\0')
-		return 1;
+		return 0;
 
 	/* Count the number of escape characters that precede ours */
 	for (ne = 0, cp = p; --cp >= sp && *cp == esc; ne++)
@@ -135,13 +135,19 @@ fparseln(FILE *fp, size_t *size, size_t *lineno, const char str[3], int flags)
 			cp = &ptr[s - 1];
 
 			if (*cp == con && !isescaped(ptr, cp, esc)) {
-				s--;	/* forget escape */
+				s--;	/* forget continuation char */
 				cnt = 1;
 			}
 		}
 
-		if (s == 0 && buf != NULL)
-			continue;
+		if (s == 0) {
+			/*
+			 * nothing to add, skip realloc except in case
+			 * we need a minimal buf to return an empty line
+			 */
+			if (cnt || buf != NULL)
+				continue;
+		}
 
 		if ((cp = realloc(buf, len + s + 1)) == NULL) {
 			free(buf);