patcht/perf: correctly align non-ASCII descriptions in output

> Change the test descriptions from being treated as binary blobs by
> perl to being treated as UTF-8. This ensures that e.g. a test
> description like "æ" is counted as 1 character, not 2.
> 
> I have WIP performance tests for non-ASCII grep patterns on another
> topic that are affected by this.

> diff --git a/t/perf/aggregate.perl b/t/perf/aggregate.perl
> index 924b19dab4..1dbc85b214 100755
> --- a/t/perf/aggregate.perl
> +++ b/t/perf/aggregate.perl
> @@ -88,6 +88,7 @@ for my $t (@tests) {
>  sub read_descr {
>  	my $name = shift;
>  	open my $fh, "<", $name or return "<error reading description>";
> +	binmode $fh, ":utf8" or die "PANIC on binmode: $!";

> On Fri, Apr 21, 2017 at 07:44:28PM +0000, Ævar Arnfjörð Bjarmason wrote:
>
>> Change the test descriptions from being treated as binary blobs by
>> perl to being treated as UTF-8. This ensures that e.g. a test
>> description like "æ" is counted as 1 character, not 2.
>>
>> I have WIP performance tests for non-ASCII grep patterns on another
>> topic that are affected by this.
>
> Makes sense. As this is purely about test titles in our project,
> choosing utf8 as the only encoding is quite sensible.

>> diff --git a/t/perf/aggregate.perl b/t/perf/aggregate.perl
>> index 924b19dab4..1dbc85b214 100755
>> --- a/t/perf/aggregate.perl
>> +++ b/t/perf/aggregate.perl
>> @@ -88,6 +88,7 @@ for my $t (@tests) {
>>  sub read_descr {
>>       my $name = shift;
>>       open my $fh, "<", $name or return "<error reading description>";
>> +     binmode $fh, ":utf8" or die "PANIC on binmode: $!";
>
> I thought there was some "use" flag we could set to just make all of our
> handles utf8. But all I could come up with was stuff like PERLIO and
> "perl -C". Using binmode isn't too bad, though (I think you could
> just do it as part of the open, too, but I'm not sure if antique
> versions of perl support that).

> > I thought there was some "use" flag we could set to just make all of our
> > handles utf8. But all I could come up with was stuff like PERLIO and
> > "perl -C". Using binmode isn't too bad, though (I think you could
> > just do it as part of the open, too, but I'm not sure if antique
> > versions of perl support that).
> 
> [Debugging perl encoding issues is one of the many perks of my dayjob]
> 
> Using binmode like this is about as straightforward as you can get,
> the former occurrence could be equivalently replaced by:
> 
>     utf8::decode(my $line = <$fh>);
> 
> But better just to mark the handle as utf8. There's a fancier way to
> do it as part of the three-arg-open syntax, but I couldn't remember
> whether all the perl versions we support have it.

> About the "use" flag, you're probably thinking of the confusingly
> named "use utf8", but that's to set your source code to utf8, not your
> handles, e.g.:
> 
> $ perl -CA -MDevel::Peek -wE 'use utf8; my $日本語 = shift; Dump $日本語' æ
> SV = PV(0x12cc090) at 0x12cded8
>   REFCNT = 1
>   FLAGS = (PADMY,POK,pPOK,UTF8)
>   PV = 0x12de460 "\303\246"\0 [UTF8 "\x{e6}"]
>   CUR = 2
>   LEN = 16
> 
> As you can see people got a bit overexcited about Unicode in the 90s.

> On Fri, Apr 21, 2017 at 11:28:42PM +0200, Ævar Arnfjörð Bjarmason wrote:
>
>> > I thought there was some "use" flag we could set to just make all of our
>> > handles utf8. But all I could come up with was stuff like PERLIO and
>> > "perl -C". Using binmode isn't too bad, though (I think you could
>> > just do it as part of the open, too, but I'm not sure if antique
>> > versions of perl support that).
>>
>> [Debugging perl encoding issues is one of the many perks of my dayjob]
>>
>> Using binmode like this is about as straightforward as you can get,
>> the former occurrence could be equivalently replaced by:
>>
>>     utf8::decode(my $line = <$fh>);
>>
>> But better just to mark the handle as utf8. There's a fancier way to
>> do it as part of the three-arg-open syntax, but I couldn't remember
>> whether all the perl versions we support have it.
>
> Yeah, I agree marking the handle is better. binmode is pretty
> straightforward, but we'd have to remember to manually set it if we add
> any other handles. That's probably not a big deal in this particular
> script, though, which is pretty short.
>
>> About the "use" flag, you're probably thinking of the confusingly
>> named "use utf8", but that's to set your source code to utf8, not your
>> handles, e.g.:
>>
>> $ perl -CA -MDevel::Peek -wE 'use utf8; my $日本語 = shift; Dump $日本語' æ
>> SV = PV(0x12cc090) at 0x12cded8
>>   REFCNT = 1
>>   FLAGS = (PADMY,POK,pPOK,UTF8)
>>   PV = 0x12de460 "\303\246"\0 [UTF8 "\x{e6}"]
>>   CUR = 2
>>   LEN = 16
>>
>> As you can see people got a bit overexcited about Unicode in the 90s.
>
> Yeah, I know "use utf8" doesn't work for that, but I was thinking there
> was some other trick. Digging...ah, here it is:
>
>   use open ':encoding(utf8)'
>
> No clue how portable that is. For such a small script it may be better
> to just stick with vanilla binmode().

> > Yeah, I know "use utf8" doesn't work for that, but I was thinking there
> > was some other trick. Digging...ah, here it is:
> >
> >   use open ':encoding(utf8)'
> >
> > No clue how portable that is. For such a small script it may be better
> > to just stick with vanilla binmode().
> 
> Yeah that would work, but doesn't work on 5.8.0, which is the lowest
> version we support.