Improve portability by adding ssize_t and long types

[jserv]

Since AMaCC was influenced by c4 design, it assumed 32-bit target. However, it is confusing while 64-bit targets are considered.

There were preliminary patches for proposed portability changes:

• Making c4 more portable for 32/64-bit compilation
• Adding more clarifications to code about what needs to be done

Expected output:

1. Adopt the previous changes to AMaCC;
2. Ensure both 32-bit and 64-bit compatibility;