kleaf: Add declarations to support building C++ host binaries. am: aea623839d

Original change: https://android-review.googlesource.com/c/platform/prebuilts/gcc/linux-x86/host/x86_64-linux-glibc2.17-4.8/+/2956134

Change-Id: Ie2247a0fa3325741419b34d21bc584e5bfdfb2bf
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>