[Build] Make sure lldb API tests run against newly built libcxx

Currently any buildbot that runs LLDB API tests does so
against the system SDK. However, we explicitly need users
to run the tests against a newly built libcxx. We recently
added a new `LLDB_TEST_LIBCXX_ROOT_DIR` CMake variable to
LLDB to allow standalone builds to point their tests to
a custom libcxx directory.

This patch makes sure the relevant LLDB presets build
libcxx and then sets above CMake variable.

(cherry picked from commit 0c974e0)

Author: Michael137

utils/build-presets.ini

@@ -291,6 +291,8 @@ skip-test-watchos-host
 
 # This is a mixin preset which builds and smoke-tests lldb.
 [preset: lldb-smoketest,tools=RA]
+# Build libcxx for tests
+libcxx
 # Build LLDB
 lldb
 
@@ -301,6 +303,8 @@ lldb-test-swift-only
 lldb-assertions
 
 [preset: lldb-pull-request]
+# Build libcxx for tests
+libcxx
 lldb
 lit-args=-v 
 

utils/build-script-impl

@@ -1709,7 +1709,7 @@ for host in "${ALL_HOSTS[@]}"; do
             libcxx)
                 build_targets=(cxx)
                 cmake_options=(
-                    -DLLVM_ENABLE_RUNTIMES="libcxx" -DLIBCXX_INSTALL_LIBRARY=OFF
+                    -DLLVM_ENABLE_RUNTIMES="libcxx;libcxxabi" -DLIBCXX_INSTALL_LIBRARY=OFF
                     "${cmake_options[@]}"
                     "${llvm_cmake_options[@]}"
                 )
@@ -2126,6 +2126,7 @@ for host in "${ALL_HOSTS[@]}"; do
                 cmark_build_dir=$(build_directory ${host} cmark)
                 lldb_build_dir=$(build_directory ${host} lldb)
                 swift_build_dir=$(build_directory ${host} swift)
+                libcxx_build_dir=$(build_directory ${host} libcxx)
 
                 # Add any lldb extra cmake arguments here.
 
@@ -2205,6 +2206,7 @@ for host in "${ALL_HOSTS[@]}"; do
                     -DLLDB_ENABLE_LZMA=OFF
                     -DLLDB_ENABLE_LUA=OFF
                     -DLLDB_INCLUDE_TESTS:BOOL=$(false_true ${BUILD_TOOLCHAIN_ONLY})
+                    -DLLDB_TEST_LIBCXX_ROOT_DIR:STRING="${libcxx_build_dir}"
                     -DLLDB_TEST_USER_ARGS="${DOTEST_ARGS}"
                 )
 
@@ -2650,10 +2652,6 @@ for host in "${ALL_HOSTS[@]}"; do
                 call env "${EXTRA_DISTCC_OPTIONS[@]}" "${CMAKE}" "${cmake_options[@]}" "${EXTRA_CMAKE_OPTIONS[@]}" "${source_dir}"
         fi
 
-        if [[ "${product}" == "libcxx" ]]; then
-            continue
-        fi
-
         # Build.
         if [[ $(not ${SKIP_BUILD}) ]]; then
             if [[ "${CMAKE_GENERATOR}" == "Xcode" ]] ; then