fix for fixup_segment / MD_PCREL_FROM_SECTION

[law@redhat.com]

  In message < 200108282007.f7SK7rG02021@phal.cambridge.redhat.com >you write:
  > Currently, it is impossible to write a port with a correct definition of
  > MD_PCREL_FROM that works, because fixup_segment neglects to subtract the
  > address of the relocation.
  > 
  > Tue Aug 28 20:37:06 2001  J"orn Rennecke <amylaar@redhat.com>
  > 
  > 	* write.c (fixup_segment): When resolving pcrel addresses,
  > 	properly subtract the address of the relocation if
  > 	TC_MD_PCREL_FROM_SECTION_FIXED is defined.
Please show me the path through fixup_segment that you're taking.  It also
seems to me that you don't need to define MD_PCREL_FROM for the port you're
working on, but that's a separate issue.

jeff