[VE] Support R_VE_RELATIVE

[kaz7]

Summary

Change getELFRelativeRelocationType() to return R_VE_RELATIVE
as a preparation of lld for VE.

llvm/lib/Object/ELF.cpp

uint32_t llvm::object::getELFRelativeRelocationType(uint32_t Machine) {
   case ELF::EM_S390:
     return ELF::R_390_RELATIVE;
   case ELF::EM_SPARC:
   case ELF::EM_SPARC32PLUS:
   case ELF::EM_SPARCV9:
     return ELF::R_SPARC_RELATIVE;
   case ELF::EM_CSKY:
     return ELF::R_CKCORE_RELATIVE;
+  case ELF::EM_VE:
+    return ELF::R_VE_RELATIVE;
   case ELF::EM_AMDGPU:
     break;
   case ELF::EM_BPF:
     break;
   default:
     break;
   }
   return 0;

llvm/unittests/Object/ELFTest.cpp

EXPECT_EQ("R_VE_TPOFF_HI32",
             getELFRelocationTypeName(EM_VE, R_VE_TPOFF_HI32));
   EXPECT_EQ("R_VE_TPOFF_LO32",
             getELFRelocationTypeName(EM_VE, R_VE_TPOFF_LO32));
   EXPECT_EQ("R_VE_CALL_HI32", getELFRelocationTypeName(EM_VE, R_VE_CALL_HI32));
   EXPECT_EQ("R_VE_CALL_LO32", getELFRelocationTypeName(EM_VE, R_VE_CALL_LO32));
 }
 
 TEST(ELFTest, getELFRelativeRelocationType) {
-  EXPECT_EQ(0U, getELFRelativeRelocationType(EM_VE));
+  EXPECT_EQ(ELF::R_VE_RELATIVE, getELFRelativeRelocationType(EM_VE));
 }
 
 // This is a test for the DataRegion helper struct, defined in ELF.h header.
 TEST(ELFTest, DataRegionTest) {
   std::vector<uint8_t> Data = {0, 1, 2};
 
   // Used to check that the operator[] works properly.
   auto CheckOperator = [&](DataRegion<uint8_t> &R) {