Configuring with --with-liburcu=qsbr won't build

The pairwise test fails with

In file included from ../../../lib/isc/include/isc/job.h:31,
                 from ../../../lib/isc/include/isc/async.h:28,
                 from ../../../lib/dns/rbtdb.c:22:
../../../lib/dns/rbtdb.c: In function 'rdataset_addglue':
../../../lib/isc/include/isc/urcu.h:113:3: error: expected expression before 'if'
  113 |   if (!urcu_qsbr_read_ongoing()) {   \
      |   ^~
../../../lib/isc/include/isc/urcu.h:120:30: note: in expansion of macro 'isc_qsbr_rcu_dereference'
  120 | #define rcu_dereference(ptr) isc_qsbr_rcu_dereference(ptr)
      |                              ^~~~~~~~~~~~~~~~~~~~~~~~
../../../lib/dns/rbtdb.c:9857:23: note: in expansion of macro 'rcu_dereference'
 9857 |  rbtdb_glue_t *glue = rcu_dereference(header->glue_list);
      |                       ^~~~~~~~~~~~~~~

for the following configuration:

--disable-developer --enable-warn-error --with-liburcu=qsbr --disable-kqueue --enable-epoll --disable-devpoll --disable-geoip --with-locktype=adaptive --enable-doh --with-libnghttp2=auto --enable-pthread-rwlock --with-gssapi=auto --with-lmdb=auto --without-libxml2 --with-json-c=detect --with-zlib=auto --without-libsystemd --enable-tcp-fastopen --with-readline=yes --enable-chroot --enable-fixed-rrset --disable-dnstap --without-libidn2 --with-cmocka=yes --without-jemalloc --disable-leak-detection --enable-singletrace --enable-querytrace --disable-auto-validation --enable-dnsrps --enable-dnsrps-dl --disable-full-report

--with-liburcu=qsbr is the culprit here.

Starts with !7895 (merged).