[examples] Fix -Wcast-qual in OrcV2Examples after D153911 (NFC)

/Users/jiefu/llvm-project/llvm/examples/OrcV2Examples/OrcV2CBindingsBasicUsage/OrcV2CBindingsBasicUsage.c:77:52: error: cast from 'char **' to 'const char **' must have all intermediate pointers const qualified to be safe [-Werror,-Wcast-qual]
  LLVMParseCommandLineOptions(argc, (const char **)argv, "");
                                                   ^
/Users/jiefu/llvm-project/llvm/examples/OrcV2Examples/OrcV2CBindingsAddObjectFile/OrcV2CBindingsAddObjectFile.c:63:52: error: cast from 'char **' to 'const char **' must have all intermediate pointers const qualified to be safe [-Werror,-Wcast-qual]
  LLVMParseCommandLineOptions(argc, (const char **)argv, "");
                                                   ^
/Users/jiefu/llvm-project/llvm/examples/OrcV2Examples/OrcV2CBindingsDumpObjects/OrcV2CBindingsDumpObjects.c:62:52: error: cast from 'char **' to 'const char **' must have all intermediate pointers const qualified to be safe [-Werror,-Wcast-qual]
  LLVMParseCommandLineOptions(argc, (const char **)argv, "");
                                                   ^
...