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/profiler.c b/src/profiler.c
index a96c1b7..64ee0ed 100644
--- a/src/profiler.c
+++ b/src/profiler.c
@@ -249,7 +249,7 @@
 /*
  * Get the current waittime.
  */
-    void
+    static void
 profile_get_wait(proftime_T *tm)
 {
     *tm = prof_wait_time;
@@ -270,7 +270,7 @@
 /*
  * Return TRUE if "tm1" and "tm2" are equal.
  */
-    int
+    static int
 profile_equal(proftime_T *tm1, proftime_T *tm2)
 {
 # ifdef MSWIN