Add risc-v support

[zinovya]

Is your feature request related to a problem? Please describe.
It is currently impossible to get deepsparce running on risc-v CPU. I was wondering if you have any plans to add support for it. We will be keen to contribute on that.

Describe the solution you'd like
compile libdeepsparse.so, deepsparse_engine.so for risc-v.

Describe alternatives you've considered
N/A.

Additional context
N/A.