fix invalid writing enum case and removing compiler warning in config.c

1] matching_name will be "uninitialized value" when value != eunm_val in rewriteConfigEnumOption
2] name will be "uninitialized value" when validSyslogFacilities[j].value != value in rewriteConfigSyslogfacilityOption
3] and removing compile error in clang, and current

in linux.
```c
config.c: In function ‘rewriteConfigEnumOption’:
config.c:1352:10: warning: ‘matching_name’ may be used uninitialized in this function [-Wmaybe-uninitialized]
config.c: In function ‘rewriteConfigSyslogfacilityOption’:
config.c:1369:10: warning: ‘name’ may be used uninitialized in this function [-Wmaybe-uninitialized]
```