grep: fix word-regexp at the beginning of lines

After bol is forwarded, it doesn't represent the beginning of the line
any more.  This means that the beginning-of-line marker (^) mustn't match,
i.e. the regex flag REG_NOTBOL needs to be set.

This bug was introduced by fb62eb7fab
("grep -w: forward to next possible position after rejected match").

Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

grep.c

@@ -360,6 +360,7 @@ static int match_one_pattern(struct grep_pat *p, char *bol, char *eol,
 			bol = pmatch[0].rm_so + bol + 1;
 			while (word_char(bol[-1]) && bol < eol)
 				bol++;
+			eflags |= REG_NOTBOL;
 			if (bol < eol)
 				goto again;
 		}