[clang] clang: Change TargetInfo::setCPU to take StringRef (PR #205278)

[LLVM Continuous Integration via cfe-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `clang-x86_64-debian-fast` running on `gribozavr4` while building `clang` at step 6 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/56/builds/2328

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

```
Step 6 (test-build-unified-tree-check-all) failure: test (failure)
******************** TEST 'lit :: shtest-not.py' FAILED ********************
Exit Code: 1

Command Output (stdout):
--
# RUN: at line 3
not env -u FILECHECK_OPTS "/usr/bin/python3.9" /b/1/clang-x86_64-debian-fast/llvm.src/llvm/utils/lit/lit.py -j1 -D use_normalized_slashes=0 --order=lexical -a Inputs/shtest-not  | FileCheck -match-full-lines /b/1/clang-x86_64-debian-fast/llvm.obj/utils/lit/tests/shtest-not.py
# executed command: not env -u FILECHECK_OPTS /usr/bin/python3.9 /b/1/clang-x86_64-debian-fast/llvm.src/llvm/utils/lit/lit.py -j1 -D use_normalized_slashes=0 --order=lexical -a Inputs/shtest-not
# executed command: FileCheck -match-full-lines /b/1/clang-x86_64-debian-fast/llvm.obj/utils/lit/tests/shtest-not.py
# .---command stderr------------
# | /b/1/clang-x86_64-debian-fast/llvm.obj/utils/lit/tests/shtest-not.py:18:10: error: CHECK: expected string not found in input
# | # CHECK: FAIL: shtest-not :: exclamation-args-none.txt {{.*}}
# |          ^
# | <stdin>:31:46: note: scanning from here
# | # error: command failed with exit status: 127
# |                                              ^
# | <stdin>:36:1: note: possible intended match here
# | FAIL: shtest-not :: exclamation-calls-external.txt (3 of 17)
# | ^
# | 
# | Input file: <stdin>
# | Check file: /b/1/clang-x86_64-debian-fast/llvm.obj/utils/lit/tests/shtest-not.py
# | 
# | -dump-input=help explains the following input dump.
# | 
# | Input was:
# | <<<<<<
# |             .
# |             .
# |             .
# |            26: ! ! ! 
# |            27: # executed command: ! ! !  
# |            28: # .---command stderr------------ 
# |            29: # | Error: '!' requires a subcommand 
# |            30: # `----------------------------- 
# |            31: # error: command failed with exit status: 127 
# | check:18'0                                                  X error: no match found
# |            32:  
# | check:18'0     ~
# |            33: -- 
# | check:18'0     ~~~
# |            34:  
# | check:18'0     ~
# |            35: ******************** 
# | check:18'0     ~~~~~~~~~~~~~~~~~~~~~
# |            36: FAIL: shtest-not :: exclamation-calls-external.txt (3 of 17) 
# | check:18'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# | check:18'1     ?                                                             possible intended match
# |            37: ******************** TEST 'shtest-not :: exclamation-calls-external.txt' FAILED ******************** 
# | check:18'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...

```

</details>

https://github.com/llvm/llvm-project/pull/205278