Avoid excessive name pollution in test files

Test files are more polite regarding the use of globals when locals
would do, and when globals are necessary deleting them after use.

testes/closure.lua

@@ -4,7 +4,7 @@
 print "testing closures"
 
 local A,B = 0,{g=10}
-function f(x)
+local function f(x)
   local a = {}
   for i=1,1000 do
     local y = 0
@@ -89,6 +89,7 @@ assert(r == "a" and s == "b")
 
 
 -- testing closures with 'for' control variable x break
+local f
 for i=1,3 do
   f = function () return i end
   break
@@ -139,7 +140,7 @@ assert(b('get') == 'xuxu')
 b('set', 10); assert(b('get') == 14)
 
 
-local w
+local y, w
 -- testing multi-level closure
 function f(x)
   return function (y)
@@ -230,6 +231,7 @@ t()
 -- test for debug manipulation of upvalues
 local debug = require'debug'
 
+local foo1, foo2, foo3
 do
   local a , b, c = 3, 5, 7
   foo1 = function () return a+b end;