New Makefile target `regen-ulps'.

New Makefile target `regen-ulps'.

The wiki "Regeneration" page has this to say about update ULPs.

"The libm-test-ulps files are semiautomatically updated. To
update an ulps baseline, run each of the failing tests (test-float,
 test-double, etc.) with -u; this will generate a file called ULPs;
concatenate each of those files with the existing libm-test-ulps
file, after removing any entries for particularly huge numbers of
ulps that you do not want to mark as expected. Then run
gen-libm-test.pl -n -u FILE where FILE is the concatenated file
produced in the previous step. This generates a file called
NewUlps which is the new sorted version of libm-test-ulps."

The same information is listed in math/README.libm-test, and is a
lot of manual work that you often want to run over-and-over again
while working on a particular test.

The `regen-ulps' convenience target does this automatically for
developers.

We strictly assume the source tree is readonly and add a
new --output-dir option to libm-test.inc to allow for writing
out ULPs to $(objpfx).

When run the new target does the following:
* Starts with the baseline ULPs file.
* Runs each of the libm math tests with -u.
* Adds new changes seen with -u to the baseline.
* Sorts and prepares the test output with gen-libm-test.pl.
* Leaves math/NewUlps in your build tree to copy to your source
  tree, cleanup, and checkin.

The math test documentation in math/README.libm-test is updated
document the new Makefile target.

---

2013-04-06  Carlos O'Donell  <carlos@redhat.com>

	* Makefile.in (regen-ulps): New target.
	* math/Makefile [ifneq (no,$(PERL)]: Declare regen-ulps with .PHONY.
	[ifneq (no,$(PERL)] (run-regen-ulps): New variable.
	[ifneq (no,$(PERL)] (regen-ulps): New target.
	[ifeq (no,$(PERL)] (regen-ulps): New target.
	* math/libm-test.inc (ulps_file_name): Define.
	(output_dir): New variable.
	(options): Add "output-dir" option.
	(parse_opt): Handle 'o' case.
	(main): If output_dir is non-NULL use it as a prefix
	otherwise use "".
	* math/README.libm-test: Update `How can I generate "libm-test-ulps"?'