initializeKeyMap() can handle ConstantAggregateZero
initializeKeyMap() can handle ConstantAggregateZero

The Byfl plug-in was crashing when given files containing lists of
constructors stored as type ConstantAggregateZero instead of type
ConstantArray.  The former seems to be produced by C++ code that
defines class constructors with empty bodies.

losalamos/Byfl,losalamos/Byfl,losalamos/Byfl,losalamos/Byfl