[ELF] Support a few more SPARCv9 relocations

Implemented a bunch of relocations found in binaries with medium/large code model and the Local-Exec TLS model. The binaries link and run fine in Qemu.
In addition, the emulation `elf64_sparc` is now recognized.

Reviewed By: MaskRay

Differential Revision: https://reviews.llvm.org/D77672