C: fix dbmopen: store $INC{AnyDBM_File} and TIEHASH

also resolve the correct $AnyDBM_File::ISA[0] by doing a compile-time AnyDBM_File->import
t/CORE: add is_perlcc_compiled(), use in op/dbm.t and op/closure.t

B::C:: is not stored anymore. check now for B::C in @DynaLoader::dl_modules

Fixes the remaining testcore regressions