ragel: use portable data types

See [1] for reason on why this is needed. In short, ARM's char is an unsigned
char and therefore C++11 won't allow storing of signed integers in there due to
new narrowing rules. The patched ragel is at [2].

[1] http://www.complang.org/pipermail/ragel-users/2013-September/002989.html
[2] http://repo.or.cz/w/ragel-jkt.git/commitdiff/dc238e78cd3024889b6fb2618fe5bbc20179a132