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: https://llvm.org/svn/llvm-project/llvm/trunk@307424 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed