* Fix `.reloc constant` to mean section_symbol+constant instead of
.+constant . The initial .reloc support from MIPS incorrectly
interpreted the offset.
* Delay the evaluation of the offset expression after
MCAssembler::layout, deleting a lot of code working with MCFragment.
* Delete many FIXME from https://reviews.llvm.org/D79625
* Some lld/ELF/Arch/LoongArch.cpp relaxation tests rely on .reloc .,
R_LARCH_ALIGN generating ALIGN relocations at specific location.
Sort the relocations.
3cb0c7f45b