riscv: Duplicated stubs to interpreter for static calls

On behalf of Dingli Zhang <dingli@iscas.ac.cn>
Follow up JDK-8280481, provides duplicated stubs to interpreter for static calls.

Calls of Java methods have stubs to the interpreter for the cases when an invoked Java method is not compiled. Calls of static Java methods and final Java methods have statically bound information about a callee during compilation. C1 and C2 always generate a new stub for each call. As the generated stubs for calls of the same method are the same, they can be shared.