fix up lldb-mi linkage on build-script-driven macOS build
fix up lldb-mi linkage on build-script-driven macOS build

lldb-mi somehow lost its dependency on zlib in build-script-driven
builds on macOS.

apple/swift-lldb,apple/swift-lldb,apple/swift-lldb,apple/swift-lldb,apple/swift-lldb,apple/swift-lldb