s3/registry: Fix incompatible func casts

s3/registry: Fix incompatible func casts

[3425/3524] Compiling source3/registry/reg_parse.c
../../source3/registry/reg_parse.c: In function ‘reg_parse_new’:
../../source3/registry/reg_parse.c:223:12: error: cast between incompatible function types from ‘int (*)(void *)’ to ‘int (*)(void *, const char **, size_t,  _Bool)’ {aka ‘int (*)(void *, const char **, long unsigned int,  _Bool)’} [-Werror=cast-function-type]
   cb.key = (reg_parse_callback_key_t)&nop;
            ^
../../source3/registry/reg_parse.c:226:12: error: cast between incompatible function types from ‘int (*)(void *)’ to ‘int (*)(void *, const char *, uint32_t,  const uint8_t *, uint32_t)’ {aka ‘int (*)(void *, const char *, unsigned int,  const unsigned char *, unsigned int)’} [-Werror=cast-function-type]
   cb.val = (reg_parse_callback_val_t)&nop;
            ^
../../source3/registry/reg_parse.c:229:16: error: cast between incompatible function types from ‘int (*)(void *)’ to ‘int (*)(void *, const char *)’ [-Werror=cast-function-type]
   cb.val_del = (reg_parse_callback_val_del_t)&nop;
                ^
../../source3/registry/reg_parse.c:232:16: error: cast between incompatible function types from ‘int (*)(void *)’ to ‘int (*)(void *, const char *)’ [-Werror=cast-function-type]
   cb.comment = (reg_parse_callback_comment_t)&nop;

Signed-off-by: Noel Power <noel.power@suse.com>
Reviewed-by: Andreas Schneider <asn@samba.org>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>