build: add rule to generate callout mappings

The callout mappings are generated at build time by a script,
which needs an input YAML file. This change enables providing such a
YAML file by the phosphor-logging recipe.

Change-Id: I8e174d60e37eabb6d26ff7822ab5c9f38d35e0a6
Signed-off-by: Deepak Kodihalli <dkodihal@in.ibm.com>
2 files changed