[JITLink][RISCV] Add names for GOT/PLT relocations

[Hahnfeld]

Summary

It is confusing to see "Unrecognized edge kind" in debugging output
for supported relocations; this was probably an oversight in commit
rG89f546f6ba which added the support.

[StephenFan]

LGTM.

llvm/lib/ExecutionEngine/JITLink/riscv.cpp

const char *getEdgeKindName(Edge::Kind K) {
   case R_RISCV_PCREL_LO12_I:
     return "R_RISCV_PCREL_LO12_I";
   case R_RISCV_PCREL_LO12_S:
     return "R_RISCV_PCREL_LO12_S";
   case R_RISCV_CALL:
     return "R_RISCV_CALL";
   case R_RISCV_32_PCREL:
     return "R_RISCV_32_PCREL";
+  case R_RISCV_GOT_HI20:
+    return "R_RISCV_GOT_HI20";
+  case R_RISCV_CALL_PLT:
+    return "R_RISCV_CALL_PLT";
   case R_RISCV_ADD64:
     return "R_RISCV_ADD64";
   case R_RISCV_ADD32:
     return "R_RISCV_ADD32";
   case R_RISCV_ADD16:
     return "R_RISCV_ADD16";
   case R_RISCV_ADD8:
     return "R_RISCV_ADD8";