Collator::createInstance crashes in optimized code if makeInstance fails

Collator::createInstance includes this code:

• makeInstance either returns NULL with U_FAILURE(status), or non-NULL with U_SUCCESS(status).

• setAttributesFromKeywords returns immediately if U_FAILURE(status), so in that case it does not actually use *coll.

• however the fact that coll is dereferenced, even if not used, allows a C++ compiler to legally optimize the NULL check out of the implementation of delete.

• so a makeInstance failure (e.g. from a bad collation keyword such as "ja@collation=private-kana") will cause such optimized code to crash.

One fix is just to add

before the setAttributesFromKeywords call.