Move io to C library

update the error reporting to include cgraph errors (could use more work)
update ggen_vname to use standard parameter order
update builtin-* to use new functions
move graph io functions to io.c file
remove code in utils
update io code to use GGEN_CHECK*
[fix] small warning fixes, make check failures

-Werror -std=c99 showed some basic errors. Nothing too bad.
make check was failing because of updated macro