[RenderScript] Enable untyped variants of Allocation-copy functions for FLOAT_16

http://b/27251511

Handle FLOAT_16 case to PER_ARRAY_TYPE macro to enable untyped variants
of Allocation-copy functions.

Untyped variants of Allocation-copy functions call
validateObjectIsPrimitiveArray(), with checkType parameter set to true,
to validate and obtain the Element type of the Allocation.  When
checkType is true, validateObjectIsPrimitiveArray() returns the actual
Element type of the Allocation (instead of the canonical SIGNED type).
Because of this, FLOAT_16 element type can reach the JNI layer,
necessitating this change to PER_ARRAY_TYPE macro.

Change-Id: I3651e5ae0ab0cd6bb4ad3157841e2910ac8699dc