ntp: disable format string warnings in libopts

[emaste]

Summary

libopts uses generated format string tables that contain embedded NULs.

example error contrib/ntp/sntp/libopts/enum.c:112:38: warning: format string contains '\0' within the string body [-Wformat]
comes from

/*  -*- buffer-read-only: t -*- vi: set ro:
 *
 * DO NOT EDIT THIS FILE   (ao-strs.h)
 *
 * It has been AutoGen-ed
 * From the definitions    ao-strs.def
 * and the template file   strings
...
/*
 * 142 strings in ao_strs_strtable string table
 */
#define ARG_BREAK_STR         (ao_strs_strtable+261)
#define ARG_BREAK_STR_LEN     5
#define ARG_BY_NUM_FMT        (ao_strs_strtable+267)
#define ARG_BY_NUM_FMT_LEN    9
#define BOOL_ATR_FMT          (ao_strs_strtable+876)
#define BOOL_ATR_FMT_LEN      31
#define CHK_MAX_COUNT         (ao_strs_strtable+1427)
#define CHK_MAX_COUNT_LEN     190
...

[dim]

There's NO_WFORMAT for this particular purpose, in share/mk/bsd.sys.mk:

.if defined(NO_WFORMAT) || defined(NO_WFORMAT.${COMPILER_TYPE})
CWARNFLAGS+=    -Wno-format
.endif # NO_WFORMAT || NO_WFORMAT.${COMPILER_TYPE}

E.g. just adding a line:

NO_WFORMAT=

should do the trick!

[emaste]

Use NO_WFORMAT as suggested by @dim