Change the "attach" command to always wait synchronously for the target to stop.  It's not very useful to return the prompt in mid-attach, and it makes reporting the result of the attach hard to do.
Change the "attach" command to always wait synchronously for the target to stop.  It's not very useful to return the prompt in mid-attach, and it makes reporting the result of the attach hard to do.

git-svn-id: b33bab8abb5b18c12ee100cd7761ab452d00b2b0@139764 91177308-0d34-0410-b5e6-96231b3b80d8

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