fix several problems with config parser:

 a bug where it underflows the string
 a bug where it never frees parser_t struct
make read_config() return 0 if parser is NULL,
 make config_close() accept and ignore NULL parser -
 eliminates many if() blocks
reverse the sense of parser bit flags - negative flags
 are harder to grok.
hexdump: revert the change to use config parser, it is BIGGER
 and also requires additional quirks in parser
*: explicitly use PARSER_NORMAL instead of 0

function                                             old     new   delta
login_main                                          1575    1596     +21
config_close                                          18      29     +11
bbunpack                                             383     391      +8
qgravechar                                           106     109      +3
rtnl_tab_initialize                                  121     117      -4
expand                                              1697    1693      -4
man_main                                             717     712      -5
nameif_main                                          674     668      -6
hexdump_main                                         597     591      -6
read_config                                          217     209      -8
dnsd_main                                           1478    1470      -8
sysctl_main                                          203     189     -14
config_open2                                          44      25     -19
make_device                                         1177    1141     -36
config_read                                          597     549     -48
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 4/11 up/down: 43/-158)         Total: -115 bytes

1 files changed, 1 insertions, 5 deletions

diff --git a/util-linux/mdev.c b/util-linux/mdev.c
index f6440b190..d0d010382 100644
--- a/util-linux/mdev.c
+++ b/util-linux/mdev.c
@@ -107,10 +107,7 @@ static void make_device(char *path, int delete)
 	parser = config_open2("/etc/mdev.conf", fopen_for_read);
 
 	/* If we have config file, look up user settings */
-	if (!parser)
-		goto end_parse;
-
-	while (config_read(parser, tokens, 4, 3, "# \t", PARSE_LAST_IS_GREEDY)) {
+	while (config_read(parser, tokens, 4, 3, "# \t", PARSE_NORMAL)) {
 		regmatch_t off[1 + 9*ENABLE_FEATURE_MDEV_RENAME_REGEXP];
 		char *val;
 
@@ -244,7 +241,6 @@ static void make_device(char *path, int delete)
 	} /* end of "while line is read from /etc/mdev.conf" */
 
 	config_close(parser);
- end_parse:
 #endif /* ENABLE_FEATURE_MDEV_CONF */
 
 	if (!delete && sscanf(dev_maj_min, "%u:%u", &major, &minor) == 2) {