[RFC] Darwin port (Part 0)

[Tristan Gingold <gingold@adacore.com>]

Hello,

here are a patch to add a new host/target: Darwin (or MacOS X).

Only a minimal set of features has been implemented: x86 and x86_64  
only (not ppc),
no support for core files, no support for fat files, no support for  
dynamic libraries,
no support for stabs (dwarf only).

The mach-o reader can handle dsym files and in object files dwarf -  
but both need to be improved.

Even all these restrictions I think the port is in good shape enough  
to be merged.  I have made
the minimal changes to common files in order to ease the merge.  Some  
planned changes (particularly
in the mach-o reader) will require modification to some common files  
and I'd prefer a first merge
before.

Two majors components (machoread.c and macosx-nat.c) have been  
rewritten from scratch but other
files (mainly i386-macosx-*.?) comes from Apple own branch of gdb.  As  
the Apple branch have never
been formally submitted the copyright status is not clear: I don't  
know if we can assume they have
been assigned to the FSF.  We have tried to contact Apple - but  
without success.  I am ready to rewrite
them in case of issue.

Also, this is my first contribution to gdb.  Comments will be very  
useful to me but please don't be
too harsh :-)

Tristan.

gdb:/
2008-11-10  Tristan Gingold  <gingold@adacore.com>

	* configure.host: Add Darwin host.
	* configure.tgt: Add Darwin target.
	* defs.h (enum gdb_osabi): Add GDB_OSABI_DARWIN and
	GDB_OSABI_DARWIN64.
	* osabi.c (gdb_osabi_names): Add names for darwin abis.
	* i386-macosx-nat.c: New file.
	* i386-macosx-tdep.c: New file.
	* i386-macosx-tdep.h: New file.
	* machoread.c: New file.
	* macosx-nat-info.c: New file.
	* macosx-nat.c: New file.
	* macosx-nat.h: New file.
	* macosx.defs: New file.
	* config/nm-macosx.h: New file.
	* config/i386/macosx.mh: New file.
	* config/i386/nm-i386-macosx.h: New file.