examples: beware of shell portability issues

Some shells don't grok `local var=$val` very well: they need the rhs
to be quoted.

    ./examples/test: 66: local: you.,: bad variable name
    FAIL examples/variant.test (exit status: 2)

Reported by Étienne Renault.

* examples/test (run): Quote the values in 'local' assignments.

examples/test

@@ -60,10 +60,10 @@ cd $$.dir
 run ()
 {
   # Expected exit status.
-  local sta_exp=$1
+  local sta_exp="$1"
   shift
   # Expected output.
-  local out_exp=$1
+  local out_exp="$1"
   shift
   # Effective exit status.
   local sta_eff=0