MIPS IRIX compatibility vs. mips-elf

[Daniel Jacobowitz]

Right now, a bunch of ld tests fail on mips-elf because .dynamic is not
first in the PT_DYNAMIC segment.  This happens because of a mismatch:
  - elf32_mips_irix_compat thinks that we are trying for Irix 5
    compatibility.  This causes _bfd_mips_elf_modify_segment_map
    to include a lot of other sections in .dynamic.
  - elf32bmip.sh thinks that this configuration is not compatible
    with Irix 5, so does not set TEXT_DYNAMIC.

As a result the .dynamic section is off in the writable segment,
causing PT_DYNAMIC to start at .dynsym, pass through .text, and reach
.dynamic (and then include an empty .data at the end, just for kicks).
The linker complains; the result is useless.

Of course, it's not quite clear what the value of mips-elf dynamic
executables is.  But it would be mildly nice if it worked, since that
gives us better test coverage for the -shared tests.  I'd like to turn
off the IRIX compat hacks for mips-elf - seems odd to include them. 
Alternately, we can just dodge the problem by disabling these tests for
mips*-elf.

Any opinions?
 
-- 
Daniel Jacobowitz