[libcxx] CI: only build native target for bootstrapping-build

Signed-off-by: Matheus Izvekov <mizvekov@gmail.com>

Reviewed By: #libc, ldionne

Differential Revision: https://reviews.llvm.org/D113950

GitOrigin-RevId: 35f798d05d5138613e1392ec1630eec93b0caff9
diff --git a/utils/ci/run-buildbot b/utils/ci/run-buildbot
index 579721f..e1b1a48 100755
--- a/utils/ci/run-buildbot
+++ b/utils/ci/run-buildbot
@@ -476,6 +476,7 @@
           -DLLVM_ENABLE_PROJECTS="clang" \
           -DLLVM_ENABLE_RUNTIMES="libcxx;libcxxabi" \
           -DLLVM_RUNTIME_TARGETS="$(c++ --print-target-triple)" \
+          -DLLVM_TARGETS_TO_BUILD="host" \
           -DRUNTIMES_BUILD_ALLOW_DARWIN=ON \
           -DLLVM_ENABLE_ASSERTIONS=ON \
           -C "${MONOREPO_ROOT}/libcxx/cmake/caches/Generic-modules.cmake" \