This PR implements the ELF support for PostLink CFG in PGO analysis map
as discussed in
[RFC](https://discourse.llvm.org/t/rfc-extending-the-pgo-analysis-map-with-propeller-cfg-frequencies/88617/2).

A later PR will implement the Codegen Support.

We have optimized the implementation of introducing the "matching and
inference" technique into Propeller. In this new implementation, we have
made every effort to avoid introducing new compilation parameters while
ensuring compatibility with Propeller's current usage. Instead of
creating a new profile format, we reused the existing one employed by
Propeller. This new implementation is fully compatible with Propeller's
current usage patterns and reduces the amount of code changes. For
detailed information, please refer to the following RFC:
https://discourse.llvm.org/t/rfc-adding-matching-and-inference-functionality-to-propeller/86238.
We plan to submit the relevant changes in several pull requests (PRs).
The current one is the first PR, which adds the basic block hash to the
SHT_LLVM_BB_ADDR_MAP section.

co-authors: lifengxiang1025 <lifengxiang@kuaishou.com>; zcfh
<wuminghui03@kuaishou.com>

Co-authored-by: lifengxiang1025 <lifengxiang@kuaishou.com>
Co-authored-by: zcfh <wuminghui03@kuaishou.com>
Co-authored-by: Rahman Lavaee <rahmanl@google.com>

Summary:
This patch has broken the `libc` build bot. I could work around that but
the changes seem unnecessary.

This reverts commit 9ba844eb3a21d461c3adc7add7691a076c6992fc.

When handling CUDA ELF files via objdump or LLDB, the ELF parser in LLVM
needs to distinguish if an ELF file is sass or not, which requires a
triple for sass to exist in llvm. This patch includes all the necessary
changes for LLDB and objdump to correctly identify these files with the
correct triple.

This PR simply moves the callsite anchors from the beginning of
callsites to their end.

Emitting the end of callsites is more sensible as it allows breaking the
basic block into subblocks which end with control transfer instructions.

Add support for big-endian RISC-V ELF files:
  - Add riscv32be/riscv64be target architectures to Triple
- Support elf32-bigriscv and elf64-bigriscv output targets in
llvm-objcopy
- Update ELFObjectFile to handle BE RISC-V format strings and
architecture detection
  - Add BE RISC-V support to RelocationResolver
  - Add tests for new functionality

This is a subset of a bigger RISC-V big-endian support patch, containing
only the llvm-objcopy and libObject changes. Other changes will be added
later.

Version 2 was added more than two years ago
(https://github.com/llvm/llvm-project/commit/6015a045d768feab3bae9ad9c0c81e118df8b04a).
So it should be safe to deprecate older versions.

Recently, we have been looking at some optimizations targeting
individual calls. In particular, we plan to extend the address mapping
technique to map to individual callsites. For example, in this piece of
code for a basic blocks:

```
<BB>:
1200:    lea 0x1(%rcx), %rdx
1204:    callq foo
1209:    cmpq 0x10, %rdx
120d:    ja  L1
```

We want to emit 0x9 as the call site offset for `callq foo` (the offset
from the block entry to right after the call), so that we know if a
sampled address is before the call or after.

This PR implements the decode/encode/emit capability. The Codegen change
will be implemented in a later PR.

This patch updates the getSectionAndRelocations function to also support
CREL relocation sections. Unit tests have been added. This patch also
updates consumers to say they explicitly do not support CREL format
relocations. Subsequent patches will make the consumers work with CREL
format relocations and also add in testing support.

Reviewers: red1bluelost, MaskRay, rlavaee

Reviewed By: MaskRay

Pull Request: https://github.com/llvm/llvm-project/pull/126445