Fix memory leak in LLVMTargetMachine.cpp

[abhishek-kaushik22]

Because MAB is a raw pointer, it could potentially leak memory because of the || in the null check.

[github-actions]

✅ With the latest revision this PR passed the C/C++ code formatter.

[abhishek-kaushik22]

@MaskRay Can you please review? In a previous commit, you made MAB a raw pointer from a unique_ptr. If this is not needed, please close.

[abhishek-kaushik22]

@KanRobert @phoebewang can you please review and merge?

[llvm-ci]

LLVM Buildbot has detected a new failure on builder llvm-clang-aarch64-darwin running on doug-worker-4 while building llvm at step 6 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/190/builds/6296

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

Step 6 (test-build-unified-tree-check-all) failure: test (failure)
******************** TEST 'LLVM-Unit :: Support/./SupportTests/4/11' FAILED ********************
Script(shard):
--
GTEST_OUTPUT=json:/Users/buildbot/buildbot-root/aarch64-darwin/build/unittests/Support/./SupportTests-LLVM-Unit-12012-4-11.json GTEST_SHUFFLE=0 GTEST_TOTAL_SHARDS=11 GTEST_SHARD_INDEX=4 /Users/buildbot/buildbot-root/aarch64-darwin/build/unittests/Support/./SupportTests
--

Script:
--
/Users/buildbot/buildbot-root/aarch64-darwin/build/unittests/Support/./SupportTests --gtest_filter=FileSystemTest.permissions
--
Test Directory: /tmp/lit-tmp-cq2haiuz/file-system-test-2f6464
/Users/buildbot/buildbot-root/aarch64-darwin/llvm-project/llvm/unittests/Support/Path.cpp:2325: Failure
Value of: CheckPermissions(fs::set_gid_on_exe)
  Actual: false
Expected: true

/Users/buildbot/buildbot-root/aarch64-darwin/llvm-project/llvm/unittests/Support/Path.cpp:2340: Failure
Value of: CheckPermissions(fs::set_uid_on_exe | fs::set_gid_on_exe | fs::sticky_bit)
  Actual: false
Expected: true

/Users/buildbot/buildbot-root/aarch64-darwin/llvm-project/llvm/unittests/Support/Path.cpp:2347: Failure
Value of: CheckPermissions(fs::all_read | fs::set_uid_on_exe | fs::set_gid_on_exe | fs::sticky_bit)
  Actual: false
Expected: true

/Users/buildbot/buildbot-root/aarch64-darwin/llvm-project/llvm/unittests/Support/Path.cpp:2350: Failure
Value of: CheckPermissions(fs::all_perms)
  Actual: false
Expected: true

/Users/buildbot/buildbot-root/aarch64-darwin/llvm-project/llvm/unittests/Support/Path.cpp:2355: Failure
Value of: CheckPermissions(fs::all_perms & ~fs::sticky_bit)
  Actual: false
Expected: true


/Users/buildbot/buildbot-root/aarch64-darwin/llvm-project/llvm/unittests/Support/Path.cpp:2325
Value of: CheckPermissions(fs::set_gid_on_exe)
  Actual: false
Expected: true

/Users/buildbot/buildbot-root/aarch64-darwin/llvm-project/llvm/unittests/Support/Path.cpp:2340
Value of: CheckPermissions(fs::set_uid_on_exe | fs::set_gid_on_exe | fs::sticky_bit)
  Actual: false
Expected: true

/Users/buildbot/buildbot-root/aarch64-darwin/llvm-project/llvm/unittests/Support/Path.cpp:2347
Value of: CheckPermissions(fs::all_read | fs::set_uid_on_exe | fs::set_gid_on_exe | fs::sticky_bit)
  Actual: false
...