C: Do not reinitialize *stdin,&stdout,*stderr twice

They are already initialized in perl.c:init_predump_symbols()

Also add testcase #185 to t/testc.sh
Add seperate threading primitives as gdb macros, my_perl is often not declared
Fix insecure unneeded -T deps for e_perlcc.t (use -O3)

-O0 adds too many unneeded dependencies which are insecure.

also intermediately silence Warning: "redo"|"last" used outside loop in CC,
appearing in all CC tests