This supersedes https://github.com/llvm/llvm-project/pull/87818 and
fixes https://github.com/llvm/llvm-project/issues/52767
When calculating arm64 thunks, we make a few assumptions that may not
hold when considering code sections outside of `__text`:
1. That a section needs thunks only if its size is larger than the
branch range.
2. That any calls into `__stubs` are necessarily forward jumps (that is,
the section with the jump is ordered before `__stubs`)
Sections like this exist in the wild, most prominently the
`__lcxx_overrides` section introduced in
https://github.com/llvm/llvm-project/pull/69498
This change:
- Ensures that if one section in `__TEXT` gets thunks, all of them do.
- Makes all code sections in `__TEXT` contiguous (and guaranteed to be
placed before `__stubs`)
58f3c5e696