This stub type loads an absolute address directly into the PC register.
It's the simplest and most compatible way to implement a branch
indirection across the entire address space (and probably the slowest as
well). It's the ideal fallback for all targets for which we did not
(yet) implement a more performant solution.
`R_ARM_PREL31` is a 31-bits relative data relocation where the
most-significant bit is preserved. It's used primarily in `.ARM.exidx`
sections, which we skipped processing until now, because we didn't
support the relocation type. This was implemented in RuntimeDyld with
https://reviews.llvm.org/D25069 and I implemented it in a similar way in
JITLink in order to reach feature parity.
All other backends use the full term "relocations". Also, sorting by type (relocations/stubs/etc.) before CPU states (arm/thumb/other) makes it easier to filter in LIT.
