remove remnants of old Mach-O workaround

remove remnants of old Mach-O workaround

I happened to run readelf on an ELF file created by Guile.  readelf
complained about invalid values for DW_FORM_strp.  At first I assumed
this was just a Guile bug, but eu-readelf did the right thing, so I
looked a bit deeper.

I came across some old Mach-O code to bias some offsets by section
addresses.  Guile, unlike many ELF writers, sets the address for the
various DWARF-related sections, causing this unusual code to be run.

This code came from an old commit:

    2005-09-30  H.J. Lu  <hongjiu.lu@intel.com>

	    * dwarf.c (fetch_indirect_string): Adjust for section address.
	    (process_debug_info): Likewise.
	    (display_debug_loc): Likewise.
	    (display_debug_ranges): Likewise.

	    * objdump.c (mach_o_dwarf_sections): New.
	    (generic_dwarf_sections): Likewise.
	    (check_mach_o_dwarf): Likewise.
	    (dump_dwarf): Call check_mach_o_dwarf.

However it was partially reverted here:

    https://sourceware.org/ml/binutils/2008-11/msg00134.html

This patch just completes the reversion.

Built and regtested on x86-64 Fedora 18.  I also ran the resulting
readelf against the Guile-created object with success.

I have no way of testing this on Mach-O, so your feedback is
solicited.

2013-12-19  Tom Tromey  <tromey@redhat.com>

	* dwarf.c (fetch_indirect_string): Don't bias by section address.
	(fetch_indexed_string): Likewise.
	(process_debug_info): Likewise.
	(display_debug_loc): Likewise.
	(display_debug_ranges): Likewise.