Remove generation of main function and inline it in __entry

[vladimirradosavljevic]

In generated __entry function, there is the simple call to main function:

define void @__entry() #16 {
entry:
  call void @main()
  br label %return

return:                                           ; preds = %entry
  call void @llvm.evm.stop()
  unreachable
}

While this is not a problem in optimized code (main function is always inlined in __entry), in non-optimized code we will run into an issue where PUSHDEPLOYADDRESS is not in the __entry function.
This should be fixed by removing main function and emit everything from that function to __entry.