Add testcase for 69a46b0

that fixed mingw but also fixed the problem for which the testcase
is now added.

tests/tests2/105_local_extern.c

@@ -0,0 +1,12 @@
+extern int printf(const char *, ...);
+void f(void);
+void bar(void) { void f(void); f(); }
+void foo(void) { extern void f(void); f(); }
+void f(void) { printf("f\n"); }
+
+int main()
+{
+  bar();
+  foo();
+  return 0;
+}

tests/tests2/105_local_extern.expect

@@ -0,0 +1,2 @@
+f
+f