Redefinition of 'hmac' as different kind of symbol on NetBSD

Since renaming hmacname to hmac in ffacf0ae BIND 9.19 won't build on NetBSD as this platform already defines hmac in the /usr/include/stdlib.h header:

CC       dig.o
In file included from dig.c:45:
./dighost.h:262:24: error: redefinition of 'hmac' as different kind of symbol
extern dst_algorithm_t hmac;
                       ^
/usr/include/stdlib.h:312:10: note: previous definition is here
ssize_t  hmac(const char *, const void *, size_t, const void *, size_t, void *,
         ^
dig.c:2461:9: error: non-object type 'ssize_t (const char *, const void *, size_t, const void *, size_t, void *, size_t)' (aka 'long (const char *, const void *, unsigned long, const void *, unsigned long, void *, unsigned long)') is not assignable
                        hmac = DST_ALG_HMACMD5;
                        ~~~~ ^
2 errors generated.

This erorr is on NetBSD 10.0 RC1 but hmac(3) suggests this will fail on every NetBSD since v8:

NAME
     hmac – compute a key-Hash Message Authentication Code
...
HISTORY
     The hmac() function appeared in NetBSD 8.