[libc++] Move the benchmarks under libcxx/test (#99371)

This is an intermediate and fairly mechanical step towards unifying the
benchmarks with the rest of the test suite. Moving this around requires
a few changes, notably making sure we don't throw a wrench into the
discovery process of the normal test suite. This won't be a problem
anymore once benchmarks are taken into account by the test setup out of
the box.

NOKEYCHECK=True
GitOrigin-RevId: 78b4b5cccbd92363708906d9171e21b0307b91a2

Author: ldionne

CMakeLists.txt

@@ -845,10 +845,6 @@ add_subdirectory(src)
 add_subdirectory(utils)
 add_subdirectory(modules)
 
-if (LIBCXX_INCLUDE_BENCHMARKS)
-  add_subdirectory(benchmarks)
-endif()
-
 if (LIBCXX_INCLUDE_TESTS)
   add_subdirectory(test)
   add_subdirectory(lib/abi)

docs/TestingLibcxx.rst

@@ -1,6 +1,10 @@
 include(HandleLitArguments)
 add_subdirectory(tools)
 
+if (LIBCXX_INCLUDE_BENCHMARKS)
+  add_subdirectory(benchmarks)
+endif()
+
 set(AUTO_GEN_COMMENT "## Autogenerated by libcxx configuration.\n# Do not edit!")
 set(SERIALIZED_LIT_PARAMS "# Lit parameters serialized here for llvm-lit to pick them up\n")
 

test/CMakeLists.txt

@@ -5,8 +5,6 @@ include(CheckCXXCompilerFlag)
 # Build Google Benchmark
 #==============================================================================
 
-set(CMAKE_FOLDER "${CMAKE_FOLDER}/Benchmarks")
-
 set(BENCHMARK_COMPILE_FLAGS
     -Wno-unused-command-line-argument
     -nostdinc++
@@ -191,6 +189,10 @@ endforeach()
 if (LIBCXX_INCLUDE_TESTS)
   include(AddLLVM)
 
+  configure_lit_site_cfg(
+          ${CMAKE_CURRENT_SOURCE_DIR}/lit.cfg.py.in
+          ${CMAKE_CURRENT_BINARY_DIR}/lit.cfg.py)
+
   configure_lit_site_cfg(
           ${CMAKE_CURRENT_SOURCE_DIR}/lit.site.cfg.py.in
           ${CMAKE_CURRENT_BINARY_DIR}/lit.site.cfg.py)