Install a diagnostic consumer into each new AST context as the first thing we do.  This prevents crashes if some of the initial setup produces messages or errors.
Install a diagnostic consumer into each new AST
context as the first thing we do.  This prevents
crashes if some of the initial setup produces
messages or errors.

<rdar://problem/20457882>


git-svn-id: 4c4cc70b1ef44ba2b7963015e681894188cea27e@234511 91177308-0d34-0410-b5e6-96231b3b80d8

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