Fixing the build command for benchmarks.

[asteinhauser]

Summary

Building libc without clang fails with:
CMake Error at /home/asteinhauser/llvm-project/libc/CMakeLists.txt:49 (message):
'clang' and 'clang-tools-extra' are required in LLVM_ENABLE_PROJECTS to
lint llvm-libc. The linting step performs important checks to help prevent
the introduction of subtle bugs, but it may increase build times.

[abrachet]

FWIW, we should do something about clang and clang-tools-extra being required. It also causes the Harbormaster builds to fail because it not longer builds all top level targets anymore.

[sivachandra]

In D80495#2061127, @abrachet wrote:

FWIW, we should do something about clang and clang-tools-extra being required. It also causes the Harbormaster builds to fail because it not longer builds all top level targets anymore.

The premerge failures were fixed with this: https://github.com/google/llvm-premerge-checks/commit/856ce4b148c19803172abde90c8c1e53673acd4d.
The latest set of failures seem to be because the premerge service is down. Are you seeing problems elsewhere?

[PaulkaToast]

In D80495#2061127, @abrachet wrote:

FWIW, we should do something about clang and clang-tools-extra being required. It also causes the Harbormaster builds to fail because it not longer builds all top level targets anymore.

If I'm not mistaken, Is this what you are referring to?

https://github.com/google/llvm-premerge-checks/commit/856ce4b148c19803172abde90c8c1e53673acd4d#diff-d6c5855a62cf32a4dadbc2831f0f295f

[abrachet]

Oh yes you two are right last I looked must have been before that change. Sorry for the noise.

libc/utils/benchmarks/README.md

 ### Run and display `memcpy` benchmark
 
 The following commands will run the benchmark and display a 95 percentile
 confidence interval curve of **time per copied bytes**. It also features **host
 informations** and **benchmarking configuration**.
 
 ```shell
 cd llvm-project
-cmake -B/tmp/build -Sllvm -DLLVM_ENABLE_PROJECTS=libc -DCMAKE_BUILD_TYPE=Release
+cmake -B/tmp/build -Sllvm -DLLVM_ENABLE_PROJECTS='clang;clang-tools-extra;libc' -DCMAKE_BUILD_TYPE=Release
 make -C /tmp/build -j display-libc-memcpy-benchmark-small
 ```
 
 The display target will attempt to open a window on the machine where you're
 running the benchmark. If this may not work for you then you may want `render`
 or `run` instead as detailed below.
 
 ## Benchmarking targets