Fix readint()
Fix readint()

There were several errors in the overflow condition and
the maximum of the type was not updated in type upgrade.

k0gaMSX/scc,k0gaMSX/scc,k0gaMSX/scc,8l/scc,k0gaMSX/kcc,8l/scc,8l/scc,k0gaMSX/kcc