Some fixes for modern Arch Linux, bison and gcc 14

[andi8086]

Here are some suggestions to make it work on modern Linux with:

• bison 3.8.2
• gcc 14.1.1

There are two fixes regarding gcc 14.1.1:

• main function of lcc must be of return type 'int'
• yylexx() must be declarated in .y otherwise gcc 14 bails out with 'implicit function declaration'

I included an example build script for linux since this was not so straight forward for me to understand, how to compile it. It also takes care of using "bison" instead of "bison -y" because "bison -y" gives warnings about not supporting "%term".

Furthermore, gram.c is generated and should hence not be in the git.