[ELF] - X86_64: Use white list for relocations checked by isPicRel.

[grimar]

Summary

isPicRel is used to check if we want to create the dynamic relocations.
Not all of the dynamic relocations we create are passing through this
check, but those that are, probably better be whitelisted.

[• espindola]

LGTM.

Thanks!

lld/trunk/ELF/Arch/X86_64.cpp

void X86_64<ELFT>::writePlt(uint8_t *Buf, uint64_t GotPltEntryAddr,
   memcpy(Buf, Inst, sizeof(Inst));
 
   write32le(Buf + 2, GotPltEntryAddr - PltEntryAddr - 6);
   write32le(Buf + 7, Index);
   write32le(Buf + 12, -getPltEntryOffset(Index) - 16);
 }
 
 template <class ELFT> bool X86_64<ELFT>::isPicRel(RelType Type) const {
-  return Type != R_X86_64_8 && Type != R_X86_64_PC8 && Type != R_X86_64_16 &&
-         Type != R_X86_64_PC16 && Type != R_X86_64_32 &&
-         Type != R_X86_64_PC32 && Type != R_X86_64_TPOFF32;
+  return Type == R_X86_64_64 || Type == R_X86_64_PC64 ||
+         Type == R_X86_64_SIZE32 || Type == R_X86_64_SIZE64;
 }
 
 template <class ELFT>
 void X86_64<ELFT>::relaxTlsGdToLe(uint8_t *Loc, RelType Type,
                                   uint64_t Val) const {
   // Convert
   //   .byte 0x66
   //   leaq x@tlsgd(%rip), %rdi