CheerpBackend: Keep track of assigned instruction ids in Registerize
CheerpBackend: Minor improvement for Registerize
CheerpBackend: Only use the label variable if required
CheerpBackend: Support bitcast between bytelayout types
CheerpBackend: Consider the bytelayout flag when comparing struct types
Hackish fix for integer correctness
CheerpBackend: Rework source maps generation
CheerpBackend: Fix slashes into source map file paths
CheerpBackend: Add support for -cheerp-sourcemap-prefix