cmake: export document_serializer_rdb

There was an error building a standalone ifcwrap when previously built IfcOpenShell had rocksdb - `_ifcopenshell_wrapper.cpython-314-x86_64-linux-gnu.so: undefined symbol: _ZTV17RocksDbSerializer`.

`IFOPSH_WITH_ROCKSDB` propagated to the build, requiring rocksdb symbols, but `WITH_ROCKSDB` wasn't set and `document_serializer_rdb` target wasn't provided.

src/ifcwrap/CMakeLists.txt

@@ -50,6 +50,7 @@ if(IFCOPENSHELL_IFCWRAP_STANDALONE)
 
     set(WITH_OPENCASCADE "${IFCOPENSHELL_WITH_OPENCASCADE}")
     set(WITH_CGAL "${IFCOPENSHELL_WITH_CGAL}")
+    set(WITH_ROCKSDB "${IFCOPENSHELL_WITH_ROCKSDB}")
     set(SWIG_DEFINES "")
 
     if(IFCOPENSHELL_WITH_OPENCASCADE)
@@ -67,6 +68,7 @@ if(IFCOPENSHELL_IFCWRAP_STANDALONE)
     if(IFCOPENSHELL_WITH_ROCKSDB)
         list(APPEND SWIG_DEFINES -DIFOPSH_WITH_ROCKSDB)
         list(APPEND _ifcwrap_feature_definitions IFOPSH_WITH_ROCKSDB)
+        add_library(document_serializer_rdb ALIAS IfcOpenShell::document_serializer_rdb)
     endif()
 endif()
 

src/serializers/CMakeLists.txt

@@ -59,6 +59,8 @@ endfunction()
 
 if(WITH_ROCKSDB)
     add_document_serializer_plugin(document_serializer_rdb "document.rdb" SOURCES document_rdb_plugin.cpp rocks_db_serializer.cpp LIBRARIES ${IFCOPENSHELL_ROCKSDB_TARGET})
+    # Still not fully a plugin and ifcwrap depends on it directly.
+    install(TARGETS document_serializer_rdb EXPORT ${IFCOPENSHELL_EXPORT_TARGETS})
 endif()
 
 add_subdirectory(schema_dependent)