ossfuzz.sh: use CXX for compiling libldac_encoder_fuzzer.cc am: ff6a91f6a8 am: d4a121864c am: 4fdacc2b91

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

Change-Id: Ic3c7337fe6efd409046df339181c429eb76e17ea
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>