utf8cache.t: Skip only the XS-dependent test

t/op/utf8cache.t

@@ -5,13 +5,15 @@ BEGIN {
     chdir 't' if -d 't';
     @INC = '../lib';
     require './test.pl';
-    skip_all_without_dynamic_extension('Devel::Peek');
 }
 
 use strict;
 
 plan(tests => 2);
 
+SKIP: {
+skip_without_dynamic_extension("Devel::Peek");
+
 my $pid = open CHILD, '-|';
 die "kablam: $!\n" unless defined $pid;
 unless ($pid) {
@@ -36,6 +38,8 @@ my $utf8magic = qr{ ^ \s+ MAGIC \s = .* \n
 
 unlike($_, qr{ $utf8magic $utf8magic }x);
 
+} # SKIP
+
 # With bad caching, this code used to go quadratic and take 10s of minutes.
 # The 'test' in this case is simply that it doesn't hang.