[clang] [clang][cmake] Add CLANG_DEFAULT_LINKER to ClangConfig.cmake.in (PR #158416)

[LLVM Continuous Integration via cfe-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `ppc64le-lld-multistage-test` running on `ppc64le-lld-multistage-test` while building `clang` at step 12 "build-stage2-unified-tree".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/168/builds/16175

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

```
Step 12 (build-stage2-unified-tree) failure: build (failure) (timed out)
...
1514.951 [56/10/6633] Linking CXX executable bin/llvm-reduce
1515.092 [56/9/6634] Linking CXX executable bin/lld
1515.140 [56/8/6635] Linking CXX executable unittests/CodeGen/CodeGenTests
1516.151 [56/7/6636] Linking CXX executable bin/opt
1517.128 [56/6/6637] Linking CXX executable bin/llvm-opt-fuzzer
1517.687 [56/5/6638] Linking CXX executable bin/llvm-split
1517.719 [56/4/6639] Linking CXX executable unittests/MIR/MIRTests
1521.089 [56/3/6640] Linking CXX executable unittests/MI/MITests
1536.823 [56/2/6641] Building CXX object tools/bugpoint-passes/CMakeFiles/BugpointPasses.dir/TestPasses.cpp.o
1538.235 [55/2/6642] Linking CXX shared module lib/BugpointPasses.so
command timed out: 1200 seconds without output running [b'ninja'], attempting to kill
process killed by signal 9
program finished with exit code -1
elapsedTime=2738.762197

```

</details>

https://github.com/llvm/llvm-project/pull/158416