For PR351:

For PR351:
* Pass sys::Path instead of std::string for paths
* Correct the types of arguments passed to RunProgramWithTimeout due to its
  interface using sys::Path instead of std::string
* Replace "/dev/null" (not portable) with empty string which
  sys::Program::ExecuteAndWait recognizes as "redirect to bit bucket"

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@19041 91177308-0d34-0410-b5e6-96231b3b80d8