aot_compiler needs to generate all llvm bitcode in order to determine the ABI requirements.

[allight]

Describe the bug
The aot_compiler needs to determine what the ABI requirements for the compiled code it generates in order to tell other users how to call it (eg alignment of input buffers, sizes, etc). These are determined while generating the llvm bitcode.

Ideally we should be able to figure out what the ABI requirements for the functions are without actually generating the entire llvm bitcode function.