multi-arch and breaking ``maintenance only'' targets (eg a29k)

[Andrew Cagney <ac131313@cygnus.com>]

Hello,

The a29k target currently builds but isn't being maintained.  Post 5.1 
it will either need to be multi-arched or will find its self dieing a 
slow death.  That death, however, may come sooner than some might think.

I'm about to post a patch that eliminates the macro HOST_BYTE_ORDER from 
GDB.  Unfortunatly the a29k target has code like:

	#ifdef TARGET_BYTE_ORDER == HOST_BYTE_ORDER
	#define MD(X)
		.....
	#else
	#define MD(X)
		.....
	#endif

and that will no longer work.  Consequently, I intend adding a #error 
... to the a29k so that it is clearly broken.

With this comes a definite shift in policy.  Up until now developers 
were to expected to keep non-multi-arch targets compiling.  If the above 
goes through, it will mean that non-multi-arch targets that are not 
being maintained can be broken on a case by case basis.

enjoy,
Andrew