Fix a few VM issues which were causing subtle failures in the test cases.

Includes a new VM method, newCall, which must be called before pushing
a call onto the stack to make sure that base is set correctly.
A couple of weird issues remain with autoload.lua.

src/test/res/autoload.lua

@@ -1,11 +1,14 @@
+-- Clear out builtin math package
+math = nil
+
 local function autoload(table, key)
-	local chunk = loadfile("/"..key..".luac")
+	local chunk = loadfile(key..".luac")
 	table[key] = chunk()
 end
 
-autoload_mt = { __index = autoload }
-
-setmetatable(_G, autoload_mt)
+setmetatable(_G, { __index = autoload } )
 
+-- local result = math.sqrt(9.0)
+-- print("x=", result)
 print("square root of 9.0 is ", math.sqrt(9.0))
 print("math.pi=", math.pi);

src/test/res/calls-expected.out

@@ -0,0 +1,4 @@
+15
+15
+1.2246467991473532E-16
+1.2246467991473532E-16

src/test/res/calls.lua

@@ -0,0 +1,24 @@
+local function f(x)
+	-- tailcall to a builtin
+	return math.sin(x)
+end
+
+local function factorial(i)
+	local function helper(sum, n)
+		if n <= 0 then
+			return sum
+		else
+			-- tail call to a nested Lua function
+			return helper(n + sum, n - 1)
+		end
+	end
+	return helper(0, i)
+end
+
+local result1 = factorial(5)
+print(result1)
+print(factorial(5))
+
+local result2 = f(math.pi)
+print(result2)
+print(f(math.pi))