vndk-def: Add more output formats to vndk command

This commit adds the --output-format option to vndk command.  When
`make` is specified, VNDK definition tool will fill in the placeholders
in the boilerplates and print a make file to stdout.

Bug: 37867089
Test: ./vndk_definition_tool.py vndk --output-format=make ...
Change-Id: I0185e1690264d0cefafa8536db2e0cf34daaeee0
5 files changed