[llvm-branch-commits] [llvm] [BOLT] Encode BAT using ULEB128 (PR #76899)

[Amir Ayupov via llvm-branch-commits]

https://github.com/aaupov created https://github.com/llvm/llvm-project/pull/76899

Reduces BAT section size, bytes:
- large binary: 38676872 -> 23262524 (0.60x),
- medium binary (trunk clang): 5938004 -> 3213504 (0.54x),
- small binary (X86/bolt-address-translation.test): 1436 -> 680 (0.47x).

Test Plan: Updated bolt/test/X86/bolt-address-translation.test