Cannot find a working 64-bit integer type on Illumos

Hi, hackers,

When I try to configure PostgreSQL 16.2 on Illumos using the following command,
it complains $subject.

    ./configure --enable-cassert --enable-debug --enable-nls --with-perl \
      --with-python --without-tcl --without-gssapi --with-openssl \
      --with-ldap --with-libxml --with-libxslt --without-systemd \
      --with-readline --enable-thread-safety --enable-dtrace \
      DTRACEFLAGS=-64 CFLAGS=-Werror

However, if I remove the `CFLAGS=-Werror`, it works fine.

I'm not sure what happened here.

$ uname -a
SunOS db_build 5.11 hunghu-20231216T132436Z i86pc i386 i86pc illumos
$ gcc --version
gcc (GCC) 10.4.0
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This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.