This fixes https://bugs.winehq.org/show_bug.cgi?id=52094.
-- v5: ntdll: Properly track refcount with forwarded exports. ntdll: Don't re-add a module dependency if it already exists. ntdll: Remove some NULL checks for current_importer. ntdll: Update current importer in LdrGetProcedureAddress(). ntdll: Wrap current_modref variable in a new structure.