* target.c (nomemory): Now that higher levels examine errno, give EIO.

* target.c (nomemory):  Now that higher levels examine errno, give EIO.
* tm-sparc.h:  Don't #include <sun4/reg.h>.
* sparc-tdep.c (sparc_frame_chain, frame_saved_pc):  Remove
dependency on <sun4/reg.h>.  Start to handle cross-byte-order.
* language.h:  Avoid forward enum declaration.
* configure.in, tm-sun4os5.h, xm-sun4os5.h, config/sun4os5.mh,
config/sun4os5.mt:  New host and target.
* defs.h (errno): #include <errno.h> rather than assuming int.
From Pierre Willard.