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

Signed-off-by: Matheus Izvekov <[email protected]>

Reviewed By: #libc, ldionne

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

Author: mizvekov

libcxx/utils/ci/run-buildbot

@@ -476,6 +476,7 @@ bootstrapping-build)
           -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" \