Use sys.executable in lldb-dotest
Use sys.executable in lldb-dotest

Without that, dotest.py would be executed with the default python
interpreter, which may not be the same one that lldb is built with.

This still requires the user do know which python interpreter to use
when running lldb-dotest, but now he is at least able to choose it, if
he knows which one to use.

git-svn-id: 4c4cc70b1ef44ba2b7963015e681894188cea27e@354105 91177308-0d34-0410-b5e6-96231b3b80d8

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