Add ANTLR4 dependencies for fasm.

[HackerFoo]

No description provided.

[litghost]

========================================
Host install packages
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Reading package lists...
Building dependency tree...
Reading state information...
E: Unable to locate package libantlr4-runtime-dev

[litghost]

I don't believe building the antlr4 runtime within the arch-defs CI is the right approach here, especially given the fact that 4 other repos will need to do the same thing. I think using a PPA to get a package or adding the dep to the litex hub conda misc are better approaches. @mithro, thoughts?

[HackerFoo]

This is a temporary fix until we have a proper package. It doesn't take long to build.

[litghost]

This is a temporary fix until we have a proper package. It doesn't take long to build.

You would have to add this temporary fix to 5 build systems, so even if it doesn't take a long time, it seems like a bad approach.

[HackerFoo]

I think this is a better solution: chipsalliance/fasm#41

[HackerFoo]

Superseded by chipsalliance/fasm#41