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/constructs.lua

@@ -11,6 +11,7 @@ local function checkload (s, msg)
 end
 
 -- testing semicollons
+local a
 do ;;; end
 ; do ; a = 3; assert(a == 3) end;
 ;
@@ -49,10 +50,10 @@ assert((((nil and true) or false) and true) == false)
 
 local a,b = 1,nil;
 assert(-(1 or 2) == -1 and (1 and 2)+(-1.25 or -4) == 0.75);
-x = ((b or a)+1 == 2 and (10 or a)+1 == 11); assert(x);
+local x = ((b or a)+1 == 2 and (10 or a)+1 == 11); assert(x);
 x = (((2<3) or 1) == true and (2<3 and 4) == 4); assert(x);
 
-x,y=1,2;
+local x, y = 1, 2;
 assert((x>y) and x or y == 2);
 x,y=2,1;
 assert((x>y) and x or y == 2);
@@ -77,13 +78,13 @@ do   -- testing operators with diffent kinds of constants
         local gab = f(o1, o2)
 
         _ENV.XX = o1
-        code = string.format("return XX %s %s", op, o2)
-        res = assert(load(code))()
+        local code = string.format("return XX %s %s", op, o2)
+        local res = assert(load(code))()
         assert(res == gab)
 
         _ENV.XX = o2
-        local code = string.format("return (%s) %s XX", o1, op)
-        local res = assert(load(code))()
+        code = string.format("return (%s) %s XX", o1, op)
+        res = assert(load(code))()
         assert(res == gab)
 
         code = string.format("return (%s) %s %s", o1, op, o2)
@@ -92,6 +93,7 @@ do   -- testing operators with diffent kinds of constants
       end
     end
   end
+  _ENV.XX = nil
 end
 
 
@@ -100,7 +102,7 @@ repeat until 1; repeat until true;
 while false do end; while nil do end;
 
 do  -- test old bug (first name could not be an `upvalue')
- local a; function f(x) x={a=1}; x={x=1}; x={G=1} end
+ local a; local function f(x) x={a=1}; x={x=1}; x={G=1} end
 end
 
 
@@ -128,7 +130,7 @@ do   -- bug since 5.4.0
 end
 
 
-function f (i)
+local function f (i)
   if type(i) ~= 'number' then return i,'jojo'; end;
   if i > 0 then return i, f(i-1); end;
 end
@@ -154,10 +156,10 @@ end
 assert(f(3) == 'a' and f(12) == 'b' and f(26) == 'c' and f(100) == nil)
 
 for i=1,1000 do break; end;
-n=100;
-i=3;
-t = {};
-a=nil
+local n=100;
+local i=3;
+local t = {};
+local a=nil
 while not a do
   a=0; for i=1,n do for i=i,1,-1 do a=a+1; t[i]=1; end; end;
 end
@@ -200,14 +202,14 @@ a={y=1}
 x = {a.y}
 assert(x[1] == 1)
 
-function f(i)
+local function f (i)
   while 1 do
     if i>0 then i=i-1;
     else return; end;
   end;
 end;
 
-function g(i)
+local function g(i)
   while 1 do
     if i>0 then i=i-1
     else return end
@@ -272,7 +274,7 @@ function g (a,b,c,d,e)
   if not (a>=b or c or d and e or nil) then return 0; else return 1; end;
 end
 
-function h (a,b,c,d,e)
+local function h (a,b,c,d,e)
   while (a>=b or c or (d and e) or nil) do return 1; end;
   return 0;
 end;
@@ -300,7 +302,7 @@ do
   assert(a==2)
 end
 
-function F(a)
+local function F (a)
   assert(debug.getinfo(1, "n").name == 'F')
   return a,2,3
 end
@@ -393,6 +395,8 @@ for n = 1, level do
     if i % 60000 == 0 then print('+') end
   end
 end
+IX = nil
+_G.GLOB1 = nil
 ------------------------------------------------------------------
 
 -- testing some syntax errors (chosen through 'gcov')