[config] fix ICU tests drop headers #1188
[config] fix ICU tests drop headers #1188

we forgot to pass the -I directives to _probe_icu.
Closes #1188

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