[libc++][Docs] Update benchmark doc wrt monorepo
authorShivam Gupta <shivam98.tkg@gmail.com>
Sat, 2 Oct 2021 02:05:15 +0000 (07:35 +0530)
committerShivam Gupta <shivam98.tkg@gmail.com>
Sat, 2 Oct 2021 02:05:32 +0000 (07:35 +0530)
commit237e9059f781d4c07ba347fa89d371346b57db44
treed5afdeb98a240fc173dab20bc5f080cfbc3c05e9
parente420164f40a907643db40e65fff51a6041d40090
[libc++][Docs] Update benchmark doc wrt monorepo

Seems this section is not updated since we have transited to llvm-project monorepo.
At the start, we build libcxx under monorepo configuration but later try to make the separate configuration for libcxx build
and running benchmark.

Reviewed By: ldionne, #libc

Differential Revision: https://reviews.llvm.org/D110722
libcxx/docs/TestingLibcxx.rst