Fix epilogue debug labels on noreturn functions
Example of remaining debug label emit bug
Don't align stack in impl_call()

The stack alignment should be kept/set in the prologue and not
altered until epilogue. VLAs should maintain this when they come.
Prevent direct memory references in -fPIC mode
impl_load() / lea doesn't dereference a type
Framework for stack-subtraction grouping
Comment on spill space
Track maximum stack size and adjust at prologue
Guard local variables from register spill overwrite

This tracks stack_sz_initial so we know where the local variables
end and where spill space can begin.
Prevent stack reclaim during function prologue
More detail on register spill comments
Test reg-spill on calls
Function call stack space is handled on epilogue/prologue
Fix non-register argument stack placement
Remove v_dealloc_stack() and handle x86 callee-pops
Handle alloc_stack_n() for word/arg pushing

This tracks the alloc_n space, so we know how much to not reserve
during function prologue, as it's implicitly done by push insns.
Fix type handling for va_arg() stack variant
Factored out same types in va_arg() code
out_deref() checks type completeness
out_ctx looks after debug variables