fix: set default SYSCONFDIR to the quasi-standard /etc/postgresql-common

Fix #1365.

NEWS

@@ -8,6 +8,8 @@ What's new in psycopg 2.9.4
   `~psycopg2.extras.register_range()` with customized search_path
   (:ticket:`#1487`).
 - Handle correctly composite types with names or in schemas requiring escape.
+- Find ``pg_service.conf file in the ``/etc/postgresql-common`` in binary
+  packages (:ticket:`1365`).
 - `~psycopg2.errorcodes` map and `~psycopg2.errors` classes updated to
   PostgreSQL 15.
 - Wheel package compiled against OpenSSL 1.1.1q and PostgreSQL 14.4

scripts/build/build_libpq.sh

@@ -117,7 +117,8 @@ if [ ! -d "${postgres_dir}" ]; then
     fi
 
     ./configure --prefix=/usr/local --without-readline \
-        --with-gssapi --with-openssl --with-pam --with-ldap
+        --with-gssapi --with-openssl --with-pam --with-ldap \
+        --sysconfdir=/etc/postgresql-common
     make -C src/interfaces/libpq
     make -C src/bin/pg_config
     make -C src/include