[gc] protect pcc_reuse_continuation from empty data
[gc] protect pcc_reuse_continuation from empty data

check for uninitialized continuation->data and allocate fresh then also.
simplify code a bit.

FROGGS/parrot,FROGGS/parrot,youprofit/parrot,tkob/parrot,FROGGS/parrot,tkob/parrot,FROGGS/parrot,youprofit/parrot,FROGGS/parrot,FROGGS/parrot,parrot/parrot,tkob/parrot,tkob/parrot,parrot/parrot,tkob/parrot,parrot/parrot,youprofit/parrot,tkob/parrot,FROGGS/parrot,parrot/parrot,FROGGS/parrot,tkob/parrot,tkob/parrot,youprofit/parrot,youprofit/parrot,youprofit/parrot,parrot/parrot,youprofit/parrot,youprofit/parrot