Prior to c94f44f9 (widl: Search for
imported typelibs in the library search path.), widl looked for
tlb files in the path specified by BIN_TO_INCLUDEDIR. After that
commit, widl looks for tlb files in a subdirectory (get_pe_dir)
of BIN_TO_DLLDIR (which mingw-w64 sets to the same as
BIN_TO_INCLUDEDIR).

For compatibility with the mingw-w64 usecase, check for tlb files
in the directory specified by BIN_TO_DLLDIR without a separate
subdirectory suffix too.
Signed-off-by: Martin Storsjö <martin@martin.st>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>