Add braces, so my head doesn't explode.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@174088 91177308-0d34-0410-b5e6-96231b3b80d8
[lit] Fix bug where InternalShellError messages were discarded.
 - Also, change the exit code to match 'sh'.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@174089 91177308-0d34-0410-b5e6-96231b3b80d8