mk: enable interpretation of backslash escapes

Signed-off-by: Viller Hsiao <villerhsiao@gmail.com>
mk: remove obsolete config variables

The config variables are generated automatically by including .config

Signed-off-by: Viller Hsiao <villerhsiao@gmail.com>
Merge pull request #52 from vh21/master

mk: enable interpretation of backslash escapes