Applying strictfp to interface methods should be illegal, by analogy
with other modifiers that only make sense when there is some code to
apply to. (It istill makes sense to allow interfaces to be strictfp, because
there may well be initialization code in an interface.)

The following JCK tests actually attempt to do this:

   lang/FP/fpl003/fpl00301m25/fpl00301m25.html
   lang/FP/fpl016/fpl01601/fpl01601.html

It is unclear to me whether there should be a similar restriction
in the classfile format.

The same restriction should be applied for abstract instance methods.