test-encode: Use tr chacter classes instead of character ranges stable

test-encode: Use tr chacter classes instead of character ranges

Solaris ...

--- a/tests/test-encode	Sat Jan 23 16:54:53 2010 +0100
+++ b/tests/test-encode	Sat Jan 23 02:03:42 2010 +0100
@@ -4,11 +4,11 @@
 
 cat > .hg/hgrc <<EOF
 [encode]
-not.gz = tr a-z A-Z
+not.gz = tr [:lower:] [:upper:]
 *.gz = gzip -d
 
 [decode]
-not.gz = tr A-Z a-z
+not.gz = tr [:upper:] [:lower:]
 *.gz = gzip
 
 EOF