Ensure Scopes can compile and run on debug LLVM

[ErikMcClure]

Scopes currently fails to run with debug LLVM because it exposes a bunch of illegal IR generation. All these failures must be corrected before we can build a proper debug executable.

• Putting raw function types in globals is illegal #19
• test_map.sc failure in debug mode #20
• Invalid constexpr bitcast in tupleof() #21