OS X: Integrate CMake and osx-app.sh

Add a -cb/--create-bundle option to osx-app.sh which builds the
application bundle. Use it in Autotools. (CMake does this by default.)

Copy over linker flags from configure.ac to CMakeLists.txt to support
rpathification and code signing.

Add an osx-app custom target to CMake.

Change-Id: I6c20a1c27f8954aaea62904b7425b9312d994803
Reviewed-on: https://code.wireshark.org/review/4918
Reviewed-by: Gerald Combs <gerald@wireshark.org>