patches for mac support

[Fawzi Mohamed <fawzi dot mohamed at nokia dot com>]

Hi all,

I have worked on bug http://sourceware.org/bugzilla/show_bug.cgi?id=11488 .
Now I think that I have reached to bottom of it, and I have a set of clean patches that could use a review.

Apple gdb simply ignores the eh_frame sections for the libraries without embedded dwarf info, not using eh information (which was the first patch that I submitted) but I find that one should be able to use them, so I looked further and found the "correct" fix.
As the path to it was a bit convoluted I have done a few improvements to pieces of code that did fail as consequence of the original bug.

The "main" fix is
   http://sourceware.org/bugzilla/attachment.cgi?id=5816&action=diff
which fixes the mmaped read of sections.

I feel that
	http://sourceware.org/bugzilla/attachment.cgi?id=5817
which adds a check on the cie pointer is important and improves gdb robustness and should also go in.

	http://sourceware.org/bugzilla/attachment.cgi?id=5814
adds the forgotten ignore of routine_64 load command, and should also go in

	http://sourceware.org/bugzilla/attachment.cgi?id=5809
is something that I have seen apple does and seems reasonable, but I have not needed it, so I am not sure if it should go in

I have also noted that compiling gdb I have the following conflict in the grammar, not sure if you are aware of it

/bin/sh ../../gdb72/gdb/../ylwrap ../../gdb72/gdb/m2-exp.y y.tab.c m2-exp.c.tmp -- bison -y
conflicts: 34 shift/reduce
/Users/fawzi/dev/gdb/gdb72Build/gdb/../../gdb72/gdb/m2-exp.y:355.25-44: warning: rule never reduced because of conflicts: @2: /* empty */

ciao
Fawzi