ossfuzz.sh: use CXX for compiling libldac_encoder_fuzzer.cc

Also, chmod a+x on ossfuzz.sh to enable building the fuzzer
in oss-fuzz

Bug: 223483473
Test: Build in oss-fuzz

Change-Id: I24c037a4cb90f6e88ce31c52c5d3f49a5142e058
1 file changed