scripts: check commit formatting

scripts: check commit formatting

The git messages have three parts:
1/ the headline
2/ the explanations
3/ the footer tags

The headline helps to quickly browse an history or catch instantly the
purpose of a commit. Making it short with some consistent wording
allows to easily parse it or match some patterns.

The explanations must give some keys like the reason of the change.
Nothing can be automatically checked for this part, except line length.

The footer contains some tags to find the origin of a bug or who
was working on it.

This script is doing some basic checks mostly on parts 1 and 3.

Signed-off-by: Thomas Monjalon <thomas.monjalon@6wind.com>
Reviewed-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>