[PRELIMINARY]: base port of gdb to IBM S390

[Michael Snyder]

Hello all, 

IBM would like to submit a base port of GDB to linux running
on their s390 mainframe.  I'm lending a hand.  I don't have
changelog entries from them yet...

	[IBM -- could you submit ChangeLog entries please?]

but here is the patch.  Besides GDB, this patch affects
bfd, opcodes, and readline.  Here is a list of the GDB
files affected (I assume that those with "s390" in the
name can be accepted virtually as is).  Anyone want to
jump in and look over the configure changes?

gdb/config.sub
gdb/configure.in
gdb/breakpoint.c
gdb/config/s390/linux.mh
gdb/config/s390/linux.mt
gdb/config/s390/s390.mh
gdb/config/s390/s390.mt
gdb/config/s390/tm-linux.h
gdb/config/s390/tm-s390.h
gdb/config/s390/xm-linux.h
gdb/configure.host
gdb/configure.tgt
gdb/s390-nat.c
gdb/s390-tdep.c

Here is the complete patch as submitted to date: