[SYCL] Update ABI dump tool to disable checks with libcxx by default (#3370)

Author: Alexander Batashev

sycl/tools/abi_check.py

@@ -57,6 +57,7 @@ def dump_symbols(target_path, output):
     out.write(os.path.basename(target_path))
     # TODO properly put OS name once Windows is supported
     out.write("\n# REQUIRES: linux")
+    out.write("\n# UNSUPPORTED: libcxx")
     out.write("\n\n")
     readobj_out = subprocess.check_output([get_llvm_bin_path()+"llvm-readobj",
                                            "-t", target_path])