[LLD][ELF] - Set DF_STATIC_TLS flag for X64 target

This is the same as D57749, but for x64 target.

"ELF Handling For Thread-Local Storage" p41 says (https://www.akkadia.org/drepper/tls.pdf):
R_X86_64_GOTTPOFF relocation is used for IE TLS models.
Hence if linker sees this relocation we should add DF_STATIC_TLS flag.

Differential revision: https://reviews.llvm.org/D57821

llvm-svn: 353378