FuzzerUtilDarwin.cpp: We need to pass modifiable strings to posix_spawn

This fixes a bug where unmodifiable strings where passed to posix_spawn.

This is an attempt to unbreak the greendragon libFuzzer bot.

git-svn-id: svn://svn.chromium.org/llvm-project/llvm/trunk/lib/Fuzzer@307424 0b72dbe1-c17f-4bc7-b9db-2b4152be0356
1 file changed