Reinstate workaround for problem in CMake PostgreSQL module

The workaround removed in 00c80c7
is actually needed, because the CMake module that implements the
find_package for PostgreSQL needs the PostgreSQL server libraries
installed. But we don't need those libraries at all (just the
client libraries).

See also https://stackoverflow.com/questions/13920383/findpostgresql-cmake-wont-work-on-ubuntu

Author: joto

.github/actions/build-and-test/action.yml

@@ -16,7 +16,7 @@ runs:
 
       - name: configure
         run: |
-          CMAKE_OPTIONS="-DPostgreSQL_TYPE_INCLUDE_DIR=/usr/include -LA -DBUILD_TESTS=ON"
+          CMAKE_OPTIONS="-LA -DBUILD_TESTS=ON"
           if [ -z "${LUA_VERSION}" ]; then
             CMAKE_OPTIONS="$CMAKE_OPTIONS -DWITH_LUA=OFF"
           else

CMakeLists.txt

@@ -52,6 +52,13 @@ option(EXTERNAL_LIBOSMIUM "Do not use the bundled libosmium" OFF)
 option(EXTERNAL_PROTOZERO "Do not use the bundled protozero" OFF)
 option(EXTERNAL_FMT       "Do not use the bundled fmt"       OFF)
 
+if (NOT WIN32 AND NOT APPLE)
+    # No need for this path, just a workaround to make cmake work on all systems.
+    # Without this we need the PostgreSQL server libraries installed.
+    # https://stackoverflow.com/questions/13920383/findpostgresql-cmake-wont-work-on-ubuntu
+    set(PostgreSQL_TYPE_INCLUDE_DIR /usr/include)
+endif()
+
 set(MINIMUM_POSTGRESQL_SERVER_VERSION "9.3")
 set(MINIMUM_POSTGRESQL_SERVER_VERSION_NUM "90300")