[svn r124] Fixed another D vararg + return in ptr bug.

Fixed some nested function calls failed to resolve the context ptr.

test/bug76.d

@@ -0,0 +1,9 @@
+module bug76;
+char[] fmt(...)
+{
+    return "";
+}
+void main()
+{
+    char[] s = fmt();
+}

test/bug77.d

@@ -0,0 +1,17 @@
+module bug77;
+import std.c.string;
+void main()
+{
+    size_t len;
+    void func2()
+    {
+        char* prefix = "";
+
+        void func()
+        {
+        len = strlen(prefix);
+        assert(len == 0);
+        }
+    }
+    func2();
+}

test/strings2.d

@@ -0,0 +1,15 @@
+module strings2;
+
+import std.string;
+import std.stdio;
+
+void main()
+{
+    int i = 32;
+    auto str = format(i);
+    writefln(str);
+
+    long l = 123123;
+    str = format(l);
+    writefln(str);
+}