[build] Fix build with new bison version, by adding include.

Signed-off-by: Marko Saukko <marko.saukko@jollamobile.com>
Fix possible future breakage when Bison might drop adding ; automatically to the
action codes.

datalang.y:*: warning: a ';' might be needed at the end of action code
datalang.y:*:     future versions of Bison will not add the ';'

Signed-off-by: Marko Saukko <marko.saukko@jollamobile.com>
Merge pull request #3 from saukko/master

fix build