Have dotest.py search for test cases in its own directory by default, rather than the current directory.
Have dotest.py search for test cases in its own directory by default,
rather than the current directory.

This is required to run the test suite outside of the source tree.

git-svn-id: b33bab8abb5b18c12ee100cd7761ab452d00b2b0@133458 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/lldb,apple/swift-lldb,llvm-mirror/lldb,llvm-mirror/lldb,apple/swift-lldb,apple/swift-lldb,apple/swift-lldb,apple/swift-lldb,apple/swift-lldb,llvm-mirror/lldb,llvm-mirror/lldb