t/test.pl: TODO cc harmless regressions
C -O3: move PerlIO_cleanup behind call exit list functions
C 1.45_12: Workaround 5.18 missing ++PL_sv_objcount for global destruction

Workaround a 5.18 de-optimization which disabled ++PL_sv_objcount on bless
(ddf23d4a1ae with 5.17.11)
by adding it again if a DESTROY method exists.
This will fail since 5.18 if DESTROY is added at run-time.
Fixes issue 208 and issue 197 on 5.18 with -O3.