Implicit declaration of function 'isc__tls_free_ex' et al. on Oracle Linux 7

BIND 9.19.6 RPM packages fail to build on Oracle Linux 7: https://gitlab.isc.org/isc-private/rpms/bind/-/jobs/2845359

tls.c: In function 'isc__tls_free':
tls.c:146:2: error: implicit declaration of function 'isc__tls_free_ex' [-Werror=implicit-function-declaration]
  isc__tls_free_ex(ptr, __FILE__, __LINE__);
  ^
tls.c: In function 'isc__tls_initialize':
tls.c:169:36: error: 'isc__tls_malloc_ex' undeclared (first use in this function)
  (void)CRYPTO_set_mem_ex_functions(isc__tls_malloc_ex,
                                    ^
tls.c:169:36: note: each undeclared identifier is reported only once for each function it appears in
tls.c:170:8: error: 'isc__tls_realloc_ex' undeclared (first use in this function)
        isc__tls_realloc_ex, isc__tls_free);
        ^

This happens only when ISC_MEM_TRACKLINES is not defined. We don't see it in CI because -DISC_MEM_TRACKLINES=1 is set when --enable-developer is present.

Oracle Linux 7 has openssl-devel-1.0.2k-25.el7_9.x86_64.

The failure above is from Mock where RPM packages are being built, but I can reproduce it locally as well.

The culprit seems to be !6807 (merged).