[llvm] [CMake] Add -Wl, -z, pack-relative-relocs if supported (PR #208217)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `bolt-aarch64-ubuntu-clang` running on `bolt-worker-aarch64` while building `llvm` at step 5 "build-clang-bolt".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/128/builds/14391

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 5 (build-clang-bolt) failure: build (failure)
...
46.170 [7/3/3487] Linking CXX static library lib/libclangExtractAPI.a
46.729 [7/2/3488] Linking CXX static library lib/libclangDriver.a
46.804 [6/2/3489] Linking CXX static library lib/libclangCrossTU.a
47.407 [5/2/3490] Linking CXX static library lib/libclangStaticAnalyzerCore.a
47.411 [4/2/3491] Linking CXX static library lib/libclangCodeGen.a
48.272 [4/1/3492] Linking CXX static library lib/libclangStaticAnalyzerCheckers.a
48.347 [3/1/3493] Linking CXX static library lib/libclangStaticAnalyzerFrontend.a
48.402 [2/1/3494] Linking CXX static library lib/libclangFrontendTool.a
49.234 [1/1/3495] Linking CXX executable bin/clang-24
174.045 [0/1/3496] Creating executable symlink bin/clang
FAILED: bin/clang 
/usr/bin/cmake -E cmake_symlink_executable bin/clang-24 bin/clang && cd /home/buildbot/workspace/bolt-aarch64-ubuntu-clang/build/tools/clang/tools/driver && /usr/bin/cmake -E create_symlink clang-24 /home/buildbot/workspace/bolt-aarch64-ubuntu-clang/build/./bin/clang++ && cd /home/buildbot/workspace/bolt-aarch64-ubuntu-clang/build/tools/clang/tools/driver && /usr/bin/cmake -E create_symlink clang-24 /home/buildbot/workspace/bolt-aarch64-ubuntu-clang/build/./bin/clang-cl && cd /home/buildbot/workspace/bolt-aarch64-ubuntu-clang/build/tools/clang/tools/driver && /usr/bin/cmake -E create_symlink clang-24 /home/buildbot/workspace/bolt-aarch64-ubuntu-clang/build/./bin/clang-cpp && cd /home/buildbot/workspace/bolt-aarch64-ubuntu-clang/build/tools/clang/tools/driver && /usr/bin/python3 /home/buildbot/workspace/bolt-aarch64-ubuntu-clang/llvm-project/clang/tools/driver/../../utils/perf-training/perf-helper.py bolt-optimize --method INSTRUMENT --input /home/buildbot/workspace/bolt-aarch64-ubuntu-clang/build/bin/clang-24 --instrumented-output /home/buildbot/workspace/bolt-aarch64-ubuntu-clang/build/./bin/clang-bolt.inst --fdata /home/buildbot/workspace/bolt-aarch64-ubuntu-clang/build/tools/clang/tools/driver/../../utils/perf-training/prof.fdata --perf-training-binary-dir /home/buildbot/workspace/bolt-aarch64-ubuntu-clang/build/tools/clang/tools/driver/../../utils/perf-training --readelf /home/buildbot/workspace/bolt-aarch64-ubuntu-clang/build/bin/llvm-readobj --bolt /home/buildbot/workspace/bolt-aarch64-ubuntu-clang/build/bin/llvm-bolt --lit /home/buildbot/workspace/bolt-aarch64-ubuntu-clang/build/./bin/llvm-lit --merge-fdata /home/buildbot/workspace/bolt-aarch64-ubuntu-clang/build/bin/merge-fdata
Running: /home/buildbot/workspace/bolt-aarch64-ubuntu-clang/build/bin/llvm-bolt /home/buildbot/workspace/bolt-aarch64-ubuntu-clang/build/bin/clang-24 -o /home/buildbot/workspace/bolt-aarch64-ubuntu-clang/build/./bin/clang-bolt.inst -instrument --instrumentation-file-append-pid --instrumentation-file=/home/buildbot/workspace/bolt-aarch64-ubuntu-clang/build/tools/clang/tools/driver/../../utils/perf-training/prof.fdata
BOLT-INFO: shared object or position-independent executable detected
BOLT-INFO: Target architecture: aarch64
BOLT-INFO: BOLT version: <unknown>
BOLT-INFO: first alloc address is 0x0
BOLT-INFO: creating new program header table at address 0x8a00000, offset 0x8a00000
BOLT-INFO: enabling relocation mode
BOLT-INFO: forcing -jump-tables=move for instrumentation
BOLT-WARNING: 1 collisions detected while hashing binary objects. Use -v=1 to see the list.
BOLT-INFO: PointerAuthCFIAnalyzer ran on 2 functions. Ignored 0 functions (0.00%) because of CFI inconsistencies
BOLT-INFO: number of removed linker-inserted veneers: 0
BOLT-INFO: 0 out of 164146 functions in the binary (0.0%) have non-empty execution profile
BOLT-INSTRUMENTER: Number of indirect call site descriptors: 60770
BOLT-INSTRUMENTER: Number of indirect call target descriptors: 161875
BOLT-INSTRUMENTER: Number of function descriptors: 161875
BOLT-INSTRUMENTER: Number of branch counters: 2035634
BOLT-INSTRUMENTER: Number of ST leaf node counters: 1056536
BOLT-INSTRUMENTER: Number of direct call counters: 0
BOLT-INSTRUMENTER: Total number of counters: 3092170
BOLT-INSTRUMENTER: Total size of counters: 24737360 bytes (static alloc memory)
BOLT-INSTRUMENTER: Total size of string table emitted: 17162043 bytes in file
BOLT-INSTRUMENTER: Total size of descriptors: 230400872 bytes in file
BOLT-INSTRUMENTER: Profile will be saved to file /home/buildbot/workspace/bolt-aarch64-ubuntu-clang/build/tools/clang/tools/driver/../../utils/perf-training/prof.fdata
BOLT-INFO: removed 21592 empty blocks
BOLT-INFO: merged 4 duplicate CFG edges
BOLT-INFO: Starting stub-insertion pass
BOLT-INFO: Inserted 1474 stubs in the hot area and 0 stubs in the cold area. Shared 194329 times, iterated 4 times.
BOLT-INFO: rewritten pac-ret DWARF info in 2 out of 164444 functions (0.00%).
BOLT-INFO: padding code to 0x13400000 to accommodate hot text
BOLT-INFO: output linked against instrumentation runtime library, lib entry point is 0x16228950
BOLT-INFO: clear procedure is 0x16227550
BOLT-INFO: patched build-id (flipped last bit)
BOLT-INFO: setting __bolt_runtime_start to 0x16228950
BOLT-INFO: setting __bolt_runtime_fini to 0x162289f0
BOLT-INFO: setting __hot_start to 0x8c00000
BOLT-INFO: setting __hot_end to 0x1333e374
BOLT-INFO: runtime library finalization was hooked via DT_FINI, set to 0x162289f0

```

</details>

https://github.com/llvm/llvm-project/pull/208217