[interchange] Fix missing subroutine when MINIVEND_DISABLE_UTF8 is set

commit 0f0d8fa2b4f45fb9f5937bea61f2b4e538b4266c
Author: David Christensen <[email protected]>
Date:   Mon Nov 14 16:04:58 2016 -0600

    Fix missing subroutine when MINIVEND_DISABLE_UTF8 is set

 lib/Vend/Util.pm |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)
---
diff --git a/lib/Vend/Util.pm b/lib/Vend/Util.pm
index d492e38..2523ce7 100644
--- a/lib/Vend/Util.pm
+++ b/lib/Vend/Util.pm
@@ -28,6 +28,10 @@ unless( $ENV{MINIVEND_DISABLE_UTF8} ) {
 	require Encode;
 	import Encode qw( is_utf8 encode_utf8 );
 }
+else {
+    # sub returning false when UTF8 is disabled
+    *is_utf8 = sub { };
+}
 
 @ISA = qw(Exporter);