Handle postgresql and sqlite3 libs properly

Do not fail to compile when one of them is missing but the other one is not.

Raise an error when trying to open a database with the missing library.

see #3237

CMakeLists.txt

@@ -193,13 +193,17 @@ file(GLOB source_network
         src/network/*.[hc]pp)
 add_library(network OBJECT ${source_network})
 
-if(SQLITE3_FOUND)
+if(SQLITE3_FOUND OR PQ_FOUND)
   file(GLOB source_database
           src/database/*.[hc]pp)
   add_library(database OBJECT ${source_database})
 
-  include_directories(database ${SQLITE3_INCLUDE_DIRS})
-  include_directories(database ${PQ_INCLUDE_DIRS})
+  if(SQLITE3_FOUND)
+    include_directories(database ${SQLITE3_INCLUDE_DIRS})
+  endif()
+  if(PQ_FOUND)
+    include_directories(database ${PQ_INCLUDE_DIRS})
+  endif()
   set(USE_DATABASE TRUE)
 else()
   add_library(database OBJECT "")
@@ -267,10 +271,14 @@ if(LIBIDN_FOUND)
   target_link_libraries(test_suite ${LIBIDN_LIBRARIES})
 endif()
 if(USE_DATABASE)
-  target_link_libraries(${PROJECT_NAME} ${SQLITE3_LIBRARIES})
-  target_link_libraries(${PROJECT_NAME} ${PQ_LIBRARIES})
-  target_link_libraries(test_suite ${SQLITE3_LIBRARIES})
-  target_link_libraries(test_suite ${PQ_LIBRARIES})
+  if(SQLITE3_FOUND)
+    target_link_libraries(${PROJECT_NAME} ${SQLITE3_LIBRARIES})
+    target_link_libraries(test_suite ${SQLITE3_LIBRARIES})
+  endif()
+  if(PQ_FOUND)
+    target_link_libraries(${PROJECT_NAME} ${PQ_LIBRARIES})
+    target_link_libraries(test_suite ${PQ_LIBRARIES})
+endif()
 endif()
 
 # Define a __FILENAME__ macro with the relative path (from the base project directory)