REAPPLY [ORC] Add automatic shared library resolver for unresolved symbols. (attempt 2)

[SahilPatidar]

This PR reapplies the changes previously introduced in #148410.
It introduces a redesigned and rebuilt Cling-based auto-loading workaround that enables scanning libraries and resolving unresolved symbols within those libraries.

Fix build failures in LibraryResolverTest and silence symlink warning

This commit resolves issues observed in the build bots:

1. Silences the -Wunused-result warning by handling the return value
   of ::symlink in LibraryResolverTest.cpp. Previously, ignoring
   the return value triggered compiler warnings.

2. Fixes a linker error in OrcJITTests caused by an undefined
   symbol: llvm::yaml::convertYAML. The test setup in
   LibraryResolverTest.cpp now correctly links against the required
   LLVM YAML library symbols.

3. Fixes persistent build bot failure caused by a path difference issue.

This resolves the build failures for PR #148410 on the affected bots.

[SahilPatidar]

@dyung Could you please review the test setup part (LibraryTestEnvironment::SetUp, LibraryResolverIT::SetUp)?
In summary, the setup creates .so/.dylib files from YAML inputs in a unique temporary directory and adds the shared library path to the test fixture environment.

[llvm-ci]

LLVM Buildbot has detected a new failure on builder llvm-nvptx64-nvidia-ubuntu running on as-builder-7 while building llvm at step 6 "test-build-unified-tree-check-llvm".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/160/builds/27520

Here is the relevant piece of the build log for the reference

Step 6 (test-build-unified-tree-check-llvm) failure: test (failure)
******************** TEST 'LLVM-Unit :: ExecutionEngine/Orc/./OrcJITTests/82/219' FAILED ********************
Script(shard):
--
GTEST_OUTPUT=json:/home/buildbot/worker/as-builder-7/llvm-nvptx64-nvidia-ubuntu/build/unittests/ExecutionEngine/Orc/./OrcJITTests-LLVM-Unit-469642-82-219.json GTEST_SHUFFLE=0 GTEST_TOTAL_SHARDS=219 GTEST_SHARD_INDEX=82 /home/buildbot/worker/as-builder-7/llvm-nvptx64-nvidia-ubuntu/build/unittests/ExecutionEngine/Orc/./OrcJITTests
--

Script:
--
/home/buildbot/worker/as-builder-7/llvm-nvptx64-nvidia-ubuntu/build/unittests/ExecutionEngine/Orc/./OrcJITTests --gtest_filter=LibraryResolverIT.ScanAndResolveDependencyGraph
--
/home/buildbot/worker/as-builder-7/llvm-nvptx64-nvidia-ubuntu/llvm-project/llvm/unittests/ExecutionEngine/Orc/LibraryResolverTest.cpp:477: Failure
Expected: (numLibs) > (0u), actual: 0 vs 0
Expected at least one library scanned


/home/buildbot/worker/as-builder-7/llvm-nvptx64-nvidia-ubuntu/llvm-project/llvm/unittests/ExecutionEngine/Orc/LibraryResolverTest.cpp:477
Expected: (numLibs) > (0u), actual: 0 vs 0
Expected at least one library scanned



********************

[llvm-ci]

LLVM Buildbot has detected a new failure on builder llvm-nvptx-nvidia-ubuntu running on as-builder-7 while building llvm at step 6 "test-build-unified-tree-check-llvm".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/180/builds/27660

Here is the relevant piece of the build log for the reference

Step 6 (test-build-unified-tree-check-llvm) failure: test (failure)
******************** TEST 'LLVM-Unit :: ExecutionEngine/Orc/./OrcJITTests/79/219' FAILED ********************
Script(shard):
--
GTEST_OUTPUT=json:/home/buildbot/worker/as-builder-7/llvm-nvptx-nvidia-ubuntu/build/unittests/ExecutionEngine/Orc/./OrcJITTests-LLVM-Unit-630404-79-219.json GTEST_SHUFFLE=0 GTEST_TOTAL_SHARDS=219 GTEST_SHARD_INDEX=79 /home/buildbot/worker/as-builder-7/llvm-nvptx-nvidia-ubuntu/build/unittests/ExecutionEngine/Orc/./OrcJITTests
--

Script:
--
/home/buildbot/worker/as-builder-7/llvm-nvptx-nvidia-ubuntu/build/unittests/ExecutionEngine/Orc/./OrcJITTests --gtest_filter=LibraryResolverIT.EnumerateSymbols_IncludesUndefineds
--
/home/buildbot/worker/as-builder-7/llvm-nvptx-nvidia-ubuntu/llvm-project/llvm/unittests/ExecutionEngine/Orc/LibraryResolverTest.cpp:350: Failure
Value of: SymbolEnumerator::enumerateSymbols(libC, onEach, Opts)
  Actual: false
Expected: true


/home/buildbot/worker/as-builder-7/llvm-nvptx-nvidia-ubuntu/llvm-project/llvm/unittests/ExecutionEngine/Orc/LibraryResolverTest.cpp:350
Value of: SymbolEnumerator::enumerateSymbols(libC, onEach, Opts)
  Actual: false
Expected: true



********************

[SahilPatidar]

Looking into the bot failures. I’ll revert the changes if the fix turns out to be non-trivial.