[llvm] [bolt][aarch64] Add R_AARCH64_P32_ABS16/32 relocations (PR #143773)

[Peter Smith via llvm-commits]

smithp35 wrote:

The ILP32 relocation codes are only legal in ELFCLASS32 files https://github.com/ARM-software/abi-aa/blob/main/aaelf64/aaelf64.rst#5731relocation-names-and-class 

I recommend that you add these only if you are intending to support 32-bit ILP32 files in BOLT (presumably from a GCC ILP32 toolchain). An ELFCLASS64 file containing these relocations is not well defined as there are different codes for the same relocation in AArch64. Is it possible that someone used the ILP32 value for the relocation code (< 256) rather than the usual one https://github.com/ARM-software/abi-aa/blob/main/aaelf64/aaelf64.rst#575static-data-relocations 

https://github.com/llvm/llvm-project/pull/143773