C: skip GvNAME_HEK(gv)="" for GV, add -DF flagspv for Gv and Cv
t/testc.sh TODO failing tests
C: set initial PL_hints

fixes #193,#207,#243 ..., most warnings issues.

also: get rid of gv_fetch TRUE => GV_ADD
fix $gv->GvFLAGS as U8 single byte only logic, needed for <5.10