emugen: generate wrapper library files

Add functionality to generate a wrapper library. A wrapper library includes:
1. entry points
2. dispatch table (accessed from the library entry points)
3. dispatch table accessor callback
4. dispatch table initialization function

Note that the dispatch table initialization function used to be part of the decoder. This
change moves it to be part of the dispatch table layer where it belongs.

Change-Id: Ide6764a17cc029056f9946e778a513cdc2a49003
5 files changed