Order of macros/functions in internals.texi

[Ben Elliston]

I've been spending a fair bit of time in the GAS internals.texi document
lately.  One thing that's been driving me crazy is that the functions and
macros that a target CPU backend can define are in seemingly arbitrary
order. 

I propose that all of these tables (including the object file backends) be
sorted by item to make it easier to refer to.  Comments?

Ben