patch 8.1.1891: functions used in one file are global

Problem:    Functions used in one file are global.
Solution:   Add "static". (Yegappan Lakshmanan, closes #4840)
diff --git a/src/indent.c b/src/indent.c
index 8499b81..2ae580a 100644
--- a/src/indent.c
+++ b/src/indent.c
@@ -15,6 +15,9 @@
 
 #if defined(FEAT_CINDENT) || defined(FEAT_SMARTINDENT)
 
+static int cin_iscase(char_u *s, int strict);
+static int cin_isscopedecl(char_u *s);
+
 /*
  * Return TRUE if the string "line" starts with a word from 'cinwords'.
  */
@@ -408,7 +411,7 @@
  * Recognize a label: "label:".
  * Note: curwin->w_cursor must be where we are looking for the label.
  */
-    int
+    static int
 cin_islabel(void)		// XXX
 {
     char_u	*s;
@@ -507,7 +510,7 @@
 /*
  * Recognize a switch label: "case .*:" or "default:".
  */
-     int
+     static int
 cin_iscase(
     char_u *s,
     int strict) // Allow relaxed check of case statement for JS
@@ -560,7 +563,7 @@
 /*
  * Recognize a "public/private/protected" scope declaration label.
  */
-    int
+    static int
 cin_isscopedecl(char_u *s)
 {
     int		i;