[RISCV] Re-enable JIT support

[Hahnfeld]

Summary

Commit rG8922adf646 recently made JITTargetMachineBuilder honor the hasJIT property of the target. LLVM supports just-in-time compilation on RISC-V, so set the flag.

[StephenFan]

LGTM.

llvm/lib/Target/RISCV/TargetInfo/RISCVTargetInfo.cpp

 }
 
 Target &llvm::getTheRISCV64Target() {
   static Target TheRISCV64Target;
   return TheRISCV64Target;
 }
 
 extern "C" LLVM_EXTERNAL_VISIBILITY void LLVMInitializeRISCVTargetInfo() {
-  RegisterTarget<Triple::riscv32> X(getTheRISCV32Target(), "riscv32",
-                                    "32-bit RISC-V", "RISCV");
-  RegisterTarget<Triple::riscv64> Y(getTheRISCV64Target(), "riscv64",
-                                    "64-bit RISC-V", "RISCV");
+  RegisterTarget<Triple::riscv32, /*HasJIT=*/true> X(
+      getTheRISCV32Target(), "riscv32", "32-bit RISC-V", "RISCV");
+  RegisterTarget<Triple::riscv64, /*HasJIT=*/true> Y(
+      getTheRISCV64Target(), "riscv64", "64-bit RISC-V", "RISCV");
 }