[libcxx][CI][AIX] Switch to LLVM_ENABLE_RUNTIMES

and to the new `runtimes` top level CMakeLists.txt since the old path is now deprecated. This requires a slight adjustment of the libcxxabi CMake, since there are required macro definitions we previously got via the `llvm/CMakeList.txt` path.

Reviewed By: ldionne, #libc, #libc_abi

Differential Revision: https://reviews.llvm.org/D113403

GitOrigin-RevId: 2b416b46479d2dbe749e90d7c5344f05b4e35abc
diff --git a/test/std/thread/thread.threads/thread.thread.class/thread.thread.static/hardware_concurrency.pass.cpp b/test/std/thread/thread.threads/thread.thread.class/thread.thread.static/hardware_concurrency.pass.cpp
index 1b22ff9..65e99e0 100644
--- a/test/std/thread/thread.threads/thread.thread.class/thread.thread.static/hardware_concurrency.pass.cpp
+++ b/test/std/thread/thread.threads/thread.thread.class/thread.thread.static/hardware_concurrency.pass.cpp
@@ -7,7 +7,6 @@
 //===----------------------------------------------------------------------===//
 //
 // UNSUPPORTED: libcpp-has-no-threads
-// XFAIL: LIBCXX-AIX-FIXME
 
 // <thread>
 
diff --git a/utils/ci/run-buildbot b/utils/ci/run-buildbot
index 744d0fd..f40e3a5 100755
--- a/utils/ci/run-buildbot
+++ b/utils/ci/run-buildbot
@@ -113,13 +113,6 @@
           "${@}"
 }
 
-function generate-cmake-aix() {
-    generate-cmake-base \
-          -S "${MONOREPO_ROOT}/llvm" \
-          -DLLVM_ENABLE_PROJECTS="libcxx;libcxxabi" \
-          "${@}"
-}
-
 function check-runtimes() {
     echo "--- Installing libc++, libc++abi and libunwind to a fake location"
     ${NINJA} -vC "${BUILD_DIR}" install-cxx install-cxxabi install-unwind
@@ -623,9 +616,10 @@
     export CC=ibm-clang
     export CXX=ibm-clang++_r
     clean
-    generate-cmake-aix -C "${MONOREPO_ROOT}/libcxx/cmake/caches/AIX.cmake" \
+    generate-cmake -C "${MONOREPO_ROOT}/libcxx/cmake/caches/AIX.cmake" \
                    -DLIBCXX_TEST_CONFIG="ibm-libc++-shared.cfg.in" \
-                   -DLIBCXXABI_TEST_CONFIG="ibm-libc++abi-shared.cfg.in"
+                   -DLIBCXXABI_TEST_CONFIG="ibm-libc++abi-shared.cfg.in" \
+                   -DLLVM_ENABLE_RUNTIMES="libcxx;libcxxabi"
     # TODO: use check-runtimes once libunwind builds cleanly on AIX.
     ${NINJA} -vC "${BUILD_DIR}" install-cxx install-cxxabi
     ${NINJA} -vC "${BUILD_DIR}" check-cxx check-cxxabi