This fixes compilation on FreeBSD:
0-- Build files have been written to: /tmp/cirrus-ci-build/bitcoin-core/depends/work/build/x86_64-unknown-freebsd14.0/native_capnp/1.0.1-867405dd2c4
1Building native_capnp...
2gmake[1]: Entering directory '/tmp/cirrus-ci-build/bitcoin-core/depends/work/build/x86_64-unknown-freebsd14.0/native_capnp/1.0.1-867405dd2c4'
3[ 1%] Building CXX object src/kj/CMakeFiles/kj.dir/array.c++.o
4[ 2%] Building CXX object src/kj/CMakeFiles/kj.dir/cidr.c++.o
5/tmp/cirrus-ci-build/bitcoin-core/depends/work/build/x86_64-unknown-freebsd14.0/native_capnp/1.0.1-867405dd2c4/src/kj/cidr.c++:112:71: error: member access into incomplete type 'const struct sockaddr_in6'
6otherBits = reinterpret_cast<const struct sockaddr_in6*>(addr)->sin6_addr.s6_addr;
7^
8/tmp/cirrus-ci-build/bitcoin-core/depends/work/build/x86_64-unknown-freebsd14.0/native_capnp/1.0.1-867405dd2c4/src/kj/cidr.c++:112:51: note: forward declaration of 'sockaddr_in6'
9otherBits = reinterpret_cast<const struct sockaddr_in6*>(addr)->sin6_addr.s6_addr;
10^
11/tmp/cirrus-ci-build/bitcoin-core/depends/work/build/x86_64-unknown-freebsd14.0/native_capnp/1.0.1-867405dd2c4/src/kj/cidr.c++:123:63: error: member access into incomplete type 'const struct sockaddr_in'
12&reinterpret_cast<const struct sockaddr_in*>(addr)->sin_addr.s_addr);
13^
14/tmp/cirrus-ci-build/bitcoin-core/depends/work/build/x86_64-unknown-freebsd14.0/native_capnp/1.0.1-867405dd2c4/src/kj/cidr.c++:123:44: note: forward declaration of 'sockaddr_in'
15&reinterpret_cast<const struct sockaddr_in*>(addr)->sin_addr.s_addr);
16^
17/tmp/cirrus-ci-build/bitcoin-core/depends/work/build/x86_64-unknown-freebsd14.0/native_capnp/1.0.1-867405dd2c4/src/kj/cidr.c++:133:69: error: member access into incomplete type 'const struct sockaddr_in6'
18otherBits = reinterpret_cast<const struct sockaddr_in6*>(addr)->sin6_addr.s6_addr;
19^
20/tmp/cirrus-ci-build/bitcoin-core/depends/work/build/x86_64-unknown-freebsd14.0/native_capnp/1.0.1-867405dd2c4/src/kj/cidr.c++:133:49: note: forward declaration of 'sockaddr_in6'
21otherBits = reinterpret_cast<const struct sockaddr_in6*>(addr)->sin6_addr.s6_addr;
22^
233 errors generated.
See: https://github.com/capnproto/capnproto/commit/1c19c362b4733023dc38042481a21c22502ed593.