ossfuzz.sh: use CXX for compiling libldac_encoder_fuzzer.cc am: ff6a91f6a8 am: d4a121864c

Original change: https://android-review.googlesource.com/c/platform/external/libldac/+/2687830

Change-Id: I9b8916f16faed01d9ac8fd718a48b5dd4eef6fb1
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>