gril: Add support for OEM hooks

Support for RIL_REQUEST_OEM_HOOK_RAW. This request and the reply
encapsulate a java byte[], which is stored as size plus raw data.
plugins: Add infineon plugin

This plugin adds support for specific requests for infineon type
modems.
infineonmodem: Add OEM hooks definitions
rilmodem: Add specific infineon request

One specific infineon OEM hook is needed to retrieve the PIN/PUK
retries for that modem type.
build: Build infineon plugin
unit: Tests for OEM_HOOK_RAW requests and replies
Merge pull request #85 from alfonsosanchezbeato/infineon-oem

Infineon OEM hooks