The printf call in the device code is expanded by the compiler into a
series of hostcalls that together form a "message". This change
introduces the following functionality in the runtime:
1. Receive a generic message consisting of a series of hostcalls.
2. Process a printf message.
Change-Id: I9d667d6f91607a907a96e46cc5fca55734339747
Sameer Sahasrabuddhe