Data race in fwrite, memcpy, and free in dnstap_test with atomics disabled

GCC and Clang report TSAN errors on ~"v9.11" with dnstap enabled and atomics disabled in the dnstap_test. These errors should not come from libfstrm.so as these are suppressed. Before !4618 (merged) gets integrated see the mnowak/configure-with-enable-dnstap-by-default-v9_11 branch and set CI_REGISTRY_IMAGE=registry.gitlab.isc.org/isc-projects/images/bind9-staging.

WARNING: ThreadSanitizer: data race 
  Read of size 8 at 0x000000000001 by thread T1:
    #0 memcpy <null>
    #1 <null> <null>

  Previous write of size 8 at 0x000000000001 by main thread:
    #0 memcpy <null>
    #1 <null> <null>
    #2 dns_dt_send lib/dns/dnstap.c:780:3
    #3 send_test lib/dns/tests/dnstap_test.c:259:3
    #4 <null> <null>
    #5 __libc_start_main /build/glibc-vjB4T2/glibc-2.28/csu/../csu/libc-start.c:308:16

  Location is heap block of size 16384 at 0x000000000009 allocated by main thread:
    #0 calloc <null>
    #1 <null> <null>
    #2 send_test lib/dns/tests/dnstap_test.c:176:11
    #3 <null> <null>
    #4 __libc_start_main /build/glibc-vjB4T2/glibc-2.28/csu/../csu/libc-start.c:308:16

  Thread T2 (running) created by main thread at:
    #0 pthread_create <null>
    #1 fstrm_iothr_init <null>
    #2 send_test lib/dns/tests/dnstap_test.c:176:11
    #3 <null> <null>
    #4 __libc_start_main /build/glibc-vjB4T2/glibc-2.28/csu/../csu/libc-start.c:308:16

SUMMARY: ThreadSanitizer: data race in memcpy

WARNING: ThreadSanitizer: data race 
  Write of size 8 at 0x000000000001 by thread T1:
    #0 free <null>
    #1 <null> <null>

  Previous write of size 8 at 0x000000000001 by main thread:
    #0 malloc <null>
    #1 pack_dt lib/dns/dnstap.c:543:14
    #2 dns_dt_send lib/dns/dnstap.c:779:6
    #3 send_test lib/dns/tests/dnstap_test.c:257:3
    #4 <null> <null>
    #5 __libc_start_main /build/glibc-vjB4T2/glibc-2.28/csu/../csu/libc-start.c:308:16

  Thread T2 (running) created by main thread at:
    #0 pthread_create <null>
    #1 fstrm_iothr_init <null>
    #2 send_test lib/dns/tests/dnstap_test.c:176:11
    #3 <null> <null>
    #4 __libc_start_main /build/glibc-vjB4T2/glibc-2.28/csu/../csu/libc-start.c:308:16

SUMMARY: ThreadSanitizer: data race in free

WARNING: ThreadSanitizer: data race 
  Read of size 8 at 0x000000000001 by thread T1:
    #0 fwrite <null>
    #1 <null> <null>

  Previous write of size 8 at 0x000000000001 by main thread:
    #0 malloc <null>
    #1 pack_dt lib/dns/dnstap.c:543:14
    #2 dns_dt_send lib/dns/dnstap.c:779:6
    #3 send_test lib/dns/tests/dnstap_test.c:254:3
    #4 <null> <null>
    #5 __libc_start_main /build/glibc-vjB4T2/glibc-2.28/csu/../csu/libc-start.c:308:16

  Location is heap block of size 256 at 0x000000000001 allocated by main thread:
    #0 malloc <null>
    #1 pack_dt lib/dns/dnstap.c:543:14
    #2 dns_dt_send lib/dns/dnstap.c:779:6
    #3 send_test lib/dns/tests/dnstap_test.c:254:3
    #4 <null> <null>
    #5 __libc_start_main /build/glibc-vjB4T2/glibc-2.28/csu/../csu/libc-start.c:308:16

  Thread T2 (running) created by main thread at:
    #0 pthread_create <null>
    #1 fstrm_iothr_init <null>
    #2 send_test lib/dns/tests/dnstap_test.c:176:11
    #3 <null> <null>
    #4 __libc_start_main /build/glibc-vjB4T2/glibc-2.28/csu/../csu/libc-start.c:308:16

SUMMARY: ThreadSanitizer: data race in fwrite

I'll just disable dnstap in unit:gcc:tsan:noatomics and unit:clang:tsan:noatomics if we decide not to fix these errors given the phase ~"v9.11" is in.