Fix for rh-minimal-parachain (#141)

* Remove extern "C"

We already encountered such behavior (bug?) in pwasm-std, I believe.

* Fix `panic_fmt` signature by adding `_col`

Wrong `panic_fmt` signature can inhibit some optimizations in LTO mode.

* Add linker flags and use wasm-gc in build script

Pass --import-memory to LLD to emit wasm binary with imported memory.

Also use wasm-gc instead of wasm-build.

* Fix effective_max.

I'm not sure why it was the way it was actually.

* Recompile wasm.

* Fix indent