Few NB-FFI methods will work without sources, as many rely on
the automatic argument name -> signature mapping.
This happens the first time a method is called after startup,
and platform-specific recompilation occurs. When the argument
names are decompiled as arg1, arg2, the mapping will fail.
(Other NB methods that generate machine code without using
NB-FFI, will still work though)
Theoretically, one could solve this by internalizing the
source of all NB-FFI calling method in the method trailer* at
the end of deployment preparation process. (so no NB methods
have a chance to trigger before image save)
NB puts native code into the same trailer space, and combing
different method trailer types is currently unsupported (AFAIK),
but the transition
TrailerWithEmbeddedSource** -> TrailerWithNBCode should
happen only once.