patch 9.0.0003: functions are global while they could be local

Problem:    Functions are global while they could be local.
Solution:   Add "static".  Add a few tests. (Yegappan Lakshmanan,
            closes #10612)

src/testdir/test_quickfix.vim

@@ -3363,8 +3363,11 @@ func Test_bufoverflow()
   cgetexpr ['Compiler: ' . repeat('a', 1015), 'File1:10:Hello World']
 
   set efm=%DEntering\ directory\ %f,%f:%l:%m
-  cgetexpr ['Entering directory ' . repeat('a', 1006),
-	      \ 'File1:10:Hello World']
+  let lines =<< trim eval END
+    Entering directory $"{repeat('a', 1006)}"
+    File1:10:Hello World
+  END
+  cgetexpr lines
   set efm&vim
 endfunc