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

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

Change-Id: I51635c6a3e8aca9a88afbd95c6159ab1121b6890
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>