Launch PostgreSQL database ourselves under macOS

It is installed there but not started by default, so just launch it
ourselves.

Note that we must not use PGHOST etc variables under Mac, as the server
seems to be configured to only listen on the local socket by default, so
don't define them globally and do it only for Linux manually instead.

.github/workflows/ci.yml

@@ -69,10 +69,6 @@ jobs:
     env:
       SOCI_CI: true
       SOCI_CI_BACKEND: ${{ matrix.backend }}
-      PGHOST: localhost
-      PGPORT: 5432
-      PGUSER: postgres
-      PGPASSWORD: Password12!
       SOCI_MYSQL_ROOT_PASSWORD: root
 
     steps:
@@ -89,6 +85,20 @@ jobs:
           set_env_var SOCI_CI_BRANCH $GITHUB_REF
           set_env_var SOCI_SOURCE_DIR $GITHUB_WORKSPACE
           set_env_var SOCI_SOURCE_DIR `pwd`
+
+          case "${{runner.os}}" in
+            Linux)
+              set_env_var PGHOST localhost
+              set_env_var PGPORT 5432
+              set_env_var PGUSER postgres
+              set_env_var PGPASSWORD 'Password12!'
+              ;;
+
+            macOS)
+              set_env_var PGDATA /usr/local/var/postgres
+              ;;
+          esac
+
           if [ "${{matrix.no_boost}}" = true ]; then
             set_env_var WITH_BOOST OFF
           fi

scripts/ci/before_build_postgresql.sh

@@ -5,5 +5,11 @@
 #
 source ${SOCI_SOURCE_DIR}/scripts/ci/common.sh
 
+if [ $(uname) = Darwin ]; then
+    pg_ctl start
+    pg_isready --timeout=60
+    createuser --superuser postgres
+fi
+
 psql --version
 psql -c 'create database soci_test;' -U postgres