Remove the program class.

It was only used to implement ExecuteAndWait and ExecuteNoWait. Expose just
those two functions and make Execute and Wait implementations details.

llvm-svn: 183864
diff --git a/llvm/lib/Support/MemoryBuffer.cpp b/llvm/lib/Support/MemoryBuffer.cpp
index 82812c0..e875d11 100644
--- a/llvm/lib/Support/MemoryBuffer.cpp
+++ b/llvm/lib/Support/MemoryBuffer.cpp
@@ -419,7 +419,7 @@
   //
   // FIXME: That isn't necessarily true, we should try to mmap stdin and
   // fallback if it fails.
-  sys::Program::ChangeStdinToBinary();
+  sys::ChangeStdinToBinary();
 
   return getMemoryBufferForStream(0, "<stdin>", result);
 }