[ELF] Recognize additional relocation types

[phosek]

Summary

These are generated by the linker itself and it shouldn't treat
them as unrecognized. This was introduced in r315552 and is triggering
an error when building UBSan shared library for i386.

[ruiu]

LGTM

ELF/Arch/X86.cpp

284–302

Sort.

ELF/Arch/X86.cpp

case R_386_PC16:
     // address fits in 16 bits. That is impossible to do here. The problem is
     // that we are passed the final value, which already had the
     // current location subtracted from it.
     // We just check that Val fits in 17 bits. This misses some cases, but
     // should have no false positives.
     checkInt<17>(Loc, Val, Type);
     write16le(Loc, Val);
     break;
   case R_386_32:
   case R_386_GLOB_DAT:
   case R_386_GOT32:
   case R_386_GOT32X:
   case R_386_GOTOFF:
   case R_386_GOTPC:
   case R_386_PC32:
   case R_386_PLT32:
   case R_386_RELATIVE:
   case R_386_TLS_GD:
   case R_386_TLS_GOTIE:
   case R_386_TLS_IE:
   case R_386_TLS_LDM:
   case R_386_TLS_LDO_32:
   case R_386_TLS_LE:
   case R_386_TLS_LE_32:
+  case R_386_TLS_TPOFF:
+  case R_386_TLS_TPOFF32:
+  case R_386_TLS_DTPOFF32:
     checkInt<32>(Loc, Val, Type);
     write32le(Loc, Val);
     break;
   default:
     error(getErrorLocation(Loc) + "unrecognized reloc " + Twine(Type));
   }
 }