Make Pancake compiler always set GC to NONE

[myreen]

I read the following in Shen's BSc thesis, page 35:

Pancake inherits infrastructure from the CakeML ecosystem, including a garbage collector that our components never utilise. LionsOS drivers operate with static memory allocation and do not require garbage collection, yet the collector code is linked into every Pancake binary regardless.

The text above is true if one uses the current default configuration. However, the defaults can be overridden by giving --gc=none as an argument to the compiler binary. Still the question remains: does it ever make sense to have it be anything other than --gc=none for Pancake?

This issue is about making the Pancake compiler always set GC to NONE when compiling.