ia64 obsolescence

[Alan Modra]

ia64 was marked obsolete 2020-08-13, which means the target support is
due to be removed some time before 2.37 is released.  The reason I
gave at the time was the fact that running the ld testsuite gave 14
segmentation faults if you were running natively or with a cross
ia64-linux compiler installed.  Current sources give 13 segfaults.

I had hoped that someone who cared about ia64 would look into why ld
is segfaulting, and perhaps even fix the fails.  As far as I know,
that hasn't happened.  So, before removing ia64 support I had a look
myself, and found that reverting commit db41f6eb5234 cures all the
segfaults and looks to be good overall:
+FAIL: PR ld/22269
+FAIL: PR ld/22269 (-z dynamic-undefined-weak)
-FAIL: Build rdynamic-1
-FAIL: Build dynamic-1
-FAIL: visibility (hidden_weak)
-FAIL: visibility (hidden_weak) (PIC main)
-FAIL: visibility (protected_weak)
-FAIL: visibility (protected_weak) (PIC main)
-FAIL: weak hidden symbol DSO first

What I'd like from those of you who objected to removing ia64, is a
better evaluation of reverting the bad commit.  Native ia64 gcc and
glibc testresult differences, for example.  Alternatively, Jim's
blessing of the revert.  That might be enough to get ia64 off the
obsolete list.

-- 
Alan Modra
Australia Development Lab, IBM