Expose more renderscript native type

Currently, Renderscript only expose a subset of its
datatype within the Android system. For instance, the unsigned
versions of the vector types for bytes, int, long and short are
not defined. In addition, while the signed scalar types for
renderscript have an elementary type equivalent, there is no such
equivalence for unsigned values.

This commit defines these missing classes and defines operations
for these types.

Change-Id: I45353a3b3f304051c072472284e7aefac60d127d
Extend Rs Math library to unsigned types

The RsMath library was created to support mathematical
operations defined upon reflected data type into Java.
Additional reflected types have been introduced but the
math library has not been updated at that time.

This commit extends the math library with new operations
defined for the new reflected types.

Change-Id: I8025976b449f96dcaea90648a8114ee6d5b98e1c