[llvm] [ORC][examples][LLVM-C] Fix ThreadSafeContext to wrap existing context (PR #157366)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `cross-project-tests-sie-ubuntu` running on `doug-worker-1a` while building `llvm` at step 6 "test-build-unified-tree-check-cross-project".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/181/builds/27500

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

```
Step 6 (test-build-unified-tree-check-cross-project) failure: test (failure)
******************** TEST 'cross-project-tests :: debuginfo-tests/dexter/feature_tests/commands/perfect/expect_watch_value.cpp' FAILED ********************
Exit Code: 2

Command Output (stderr):
--
clang++ -O0 -glldb -std=gnu++11 /home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu/llvm-project/cross-project-tests/debuginfo-tests/dexter/feature_tests/commands/perfect/expect_watch_value.cpp -o /home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu/build/projects/cross-project-tests/debuginfo-tests/dexter/feature_tests/commands/perfect/Output/expect_watch_value.cpp.tmp # RUN: at line 7
+ clang++ -O0 -glldb -std=gnu++11 /home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu/llvm-project/cross-project-tests/debuginfo-tests/dexter/feature_tests/commands/perfect/expect_watch_value.cpp -o /home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu/build/projects/cross-project-tests/debuginfo-tests/dexter/feature_tests/commands/perfect/Output/expect_watch_value.cpp.tmp
"/usr/bin/python3.8" "/home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu/llvm-project/cross-project-tests/debuginfo-tests/dexter/dexter.py" test --fail-lt 1.0 -w --debugger lldb-dap --lldb-executable "/home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu/build/bin/lldb-dap"  --dap-message-log=/home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu/build/projects/cross-project-tests/debuginfo-tests/dexter/feature_tests/commands/perfect/Output/expect_watch_value.cpp.tmp.dap.log --binary /home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu/build/projects/cross-project-tests/debuginfo-tests/dexter/feature_tests/commands/perfect/Output/expect_watch_value.cpp.tmp -- /home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu/llvm-project/cross-project-tests/debuginfo-tests/dexter/feature_tests/commands/perfect/expect_watch_value.cpp | /home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu/build/bin/FileCheck --dump-input-context=999999999 /home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu/llvm-project/cross-project-tests/debuginfo-tests/dexter/feature_tests/commands/perfect/expect_watch_value.cpp # RUN: at line 8
+ /usr/bin/python3.8 /home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu/llvm-project/cross-project-tests/debuginfo-tests/dexter/dexter.py test --fail-lt 1.0 -w --debugger lldb-dap --lldb-executable /home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu/build/bin/lldb-dap --dap-message-log=/home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu/build/projects/cross-project-tests/debuginfo-tests/dexter/feature_tests/commands/perfect/Output/expect_watch_value.cpp.tmp.dap.log --binary /home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu/build/projects/cross-project-tests/debuginfo-tests/dexter/feature_tests/commands/perfect/Output/expect_watch_value.cpp.tmp -- /home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu/llvm-project/cross-project-tests/debuginfo-tests/dexter/feature_tests/commands/perfect/expect_watch_value.cpp
+ /home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu/build/bin/FileCheck --dump-input-context=999999999 /home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu/llvm-project/cross-project-tests/debuginfo-tests/dexter/feature_tests/commands/perfect/expect_watch_value.cpp
-> {
  "type": "request",
  "command": "initialize",
  "arguments": {
    "clientID": "dexter",
    "adapterID": "lldb-dap",
    "pathFormat": "path",
    "linesStartAt1": true,
    "columnsStartAt1": true,
    "supportsVariableType": true,
    "supportsVariablePaging": true,
    "supportsRunInTerminalRequest": false
  },
  "seq": 1
}
<- {
  "body": {
    "$__lldb_version": "lldb version 22.0.0git (https://github.com/llvm/llvm-project.git revision 4546522aa34c1f56a22e35cb411d4e18481d1854)\n  clang revision 4546522aa34c1f56a22e35cb411d4e18481d1854\n  llvm revision 4546522aa34c1f56a22e35cb411d4e18481d1854",
    "completionTriggerCharacters": [
      ".",
      " ",
      "\t"
    ],
    "exceptionBreakpointFilters": [
      {
        "description": "C++ Catch",
        "filter": "cpp_catch",
        "label": "C++ Catch",
        "supportsCondition": true
      },
      {
        "description": "C++ Throw",
        "filter": "cpp_throw",
        "label": "C++ Throw",
        "supportsCondition": true
      },
      {
        "description": "Objective-C Catch",
        "filter": "objc_catch",
        "label": "Objective-C Catch",
...

```

</details>

https://github.com/llvm/llvm-project/pull/157366