patch 9.0.1118: sporadic test failures when using a terminal window

Problem:    Sporadic test failures when using a terminal window.
Solution:   Adjust waiting times. (James McCoy, closes #11763)
diff --git a/src/testdir/test_search.vim b/src/testdir/test_search.vim
index e51803d..074ab15 100644
--- a/src/testdir/test_search.vim
+++ b/src/testdir/test_search.vim
@@ -375,7 +375,7 @@
   else
     let ms = 1
     let min_time = 0.001
-    let max_time = min_time * 10.0
+    let max_time = min_time * 15.0
     if RunningWithValgrind()
       let max_time += 0.04  " this can be slow with valgrind
     endif