Try to not fail when writing UTF po files with old Perl versions

This is some sort of blind attempt, but I'm rather confident
Fix #495

I still cannot reproduce this bug locally, but Ineiev tracked it down
and tested the patch proposed with Perl v5.16.3 v5.24.1 v5.26.1
v5.26.3 v5.28.1 v5.32.1 v5.34.0 v5.36.0 v5.36.3 v5.38.2. Many thanks
to them about it!

That's a bit sad that it's not part of the v0.72 but duh, that's still
a blind attempt at fixing a problem I cannot reproduce. I'm getting
too old for the last-minute commit breaking the release. I think it
can wait, or maintainers can cherry-pick it if it works for them.

NEWS

@@ -8,6 +8,9 @@ __   __/ _ \|___  |___ /
  \ V /| |_| | / /  ___) |
   \_/  \___(_)_/  |____/          (not released yet)
 
+General:
+ * Try to not fail when writing UTF po files with old Perl versions
+   (GitHub's #495) [Ineiev].
 
 =======================================================================
         ___  _____ ____

lib/Locale/Po4a/Po.pm

@@ -541,6 +541,9 @@ sub write {
           or croak wrap_mod( "po4a::po", dgettext( "po4a", "Cannot write to %s: %s" ), $filename, $! );
     }
 
+    # Some old perl versions qwak when the encoding is only set to utf. We need to first reset it to raw before setting utf8 again. Not sure why it's so.
+    binmode( $fh, ':raw' );
+    binmode( $fh, ':utf8' );
     print $fh "" . format_comment( $self->{header_comment}, "" )
       if length( $self->{header_comment} );
 
@@ -1537,7 +1540,6 @@ sub canonize {
     return $text;
 }
 
-
 # Wraps the string. We don't use Text::Wrap since it mangles whitespace at the
 # end of the split line.
 #
@@ -1549,7 +1551,7 @@ sub canonize {
 #  - The extra length allowed for the first line. Default: -10 (which means it
 #    will be wrapped 10 characters shorter).
 sub wrap {
-    my $text        = shift;
+    my $text = shift;
     return "0" if ( $text eq '0' );
     my $col         = shift || 76;
     my $first_shift = shift || -10;