Correct retain handling for floating point ops
Consume out_op/stack allocation return

This fixes the retained stack values.
Warn-unused-result was missing on a few out_* functions
Fixed ordering of impl_op() + x86_64 operand types
Correct v_stack_adj() parameter order
v_to_stack_mem() returns the stack'd value
v_save_regs() replaces old registers with the stack'd value
expr_funcall doesn't retain arguments