Revert "Remove EXPAND/STRINGIFY macros."

This reverts commit ec970673.

Reason for revert: It's not a good idea to put RECOVERY_API_VERSION in
common.h, which might be included by device-specific codes (but with
RECOVERY_API_VERSION undefined).

Change-Id: I9feb9c64a5af3e9165164622a59b043aa28a8b8c