Update dg-extract-results.* from gcc

Update dg-extract-results.* from gcc

When looking at the gdb.sum file produced by dg-extract-results.sh on
Solaris 11/x86, I noticed some wrong sorting, like this:

PASS: gdb.ada/addr_arith.exp: print something'address + 0
PASS: gdb.ada/addr_arith.exp: print 0 + something'address
PASS: gdb.ada/addr_arith.exp: print something'address - 0
PASS: gdb.ada/addr_arith.exp: print 0 - something'address

Looking closer, I noticed that while dg-extract-results.sh had been
copied over from contrib in the gcc repo, the corresponding
dg-extract-results.py file had not.  The latter not only fixes the
sorting problem I'd observed, but is also way faster than the shell
version (like a factor of 50 faster).

Therefore I propose to update both files from the gcc repo.  The changes
to the .sh version are trivial, just counting the number of DejaGnu
ERROR lines, too.

The files are moved to toplevel contrib:

* This way, they can easily be used should someone decide to parallelize
  one or more of the binutils, gas, or ld testsuites.

* They are less easily overlooked for updates from the gcc repo when
  they reside in the same place in both.

* The test_summary script needs to live in contrib since the toplevel
  Makefile's mail-report.log target expects it there.

Tested on amd64-pc-solaris2.11 with

	make -j16 check
and
	make -j16 -k RACY_ITER=5 check

	gdb/testsuite:
	* dg-extract-results.sh: Move to toplevel contrib.
	* Makefile.in (check-parallel): Reflect dg-extract-results.sh move.
	* Makefile.in (check-parallel-racy): Likewise.

	contrib:
	* dg-extract-results.sh: Move from gdb/testsuite.
	Update from gcc repo.
	* dg-extract-results.py: New from gcc repo.