utils/check-package: allow to disable warning for a line

Currently any exceptions for a check function need to be coded into the
check-package script itself.

Create a pattern that can be used in a comment to make check-package
ignore one or more warning types in the line immediately below:
 # check-package Indent, VariableWithBraces

Signed-off-by: Ricardo Martincoski <ricardo.martincoski@gmail.com>
Reviewed-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>