RFR(xs): 8172712: configure should check that grep handles empty pattern correctly

[Magnus Ihse Bursie]

Looks good to me.

Since the closed generated-configure needs to be regenerated, I'll 
sponsor and push this patch.

/Magnus

On 2017-01-12 14:04, Thomas Stüfe wrote:
> Dear all,
>
> please take a look at this fix. This should prevent configure from using a
> grep which is not able to handle pattern lists with empty patterns.
>
> Bug:
> https://bugs.openjdk.java.net/browse/JDK-8172712
>
> webrevs:
> http://cr.openjdk.java.net/~stuefe/webrevs/8172712-configure-should-check-that-grep-handles-empty-pattern-correctly/webrev.00/webrev/
>
> Background:
>
> https://bugs.openjdk.java.net/browse/JDK-8172579 was a build error caused
> by a buggy grep (on AIX) and the easiest way to work around that bug would
> be to use the GNU version of grep. It was suggested in the orginal mail
> thread (
> http://mail.openjdk.java.net/pipermail/build-dev/2017-January/018495.html)
> to check this in configure.
>
> This change implements this suggestion and checks if grep behaves correctly.
>
> Kind Regards, Thomas