patch 8.1.1955: tests contain typos

Problem:    Tests contain typos.
Solution:   Correct the typos. (Dominique Pelle)
diff --git a/src/testdir/test_const.vim b/src/testdir/test_const.vim
index d93de72..55e4492 100644
--- a/src/testdir/test_const.vim
+++ b/src/testdir/test_const.vim
@@ -125,7 +125,7 @@
     unlet s:x
 endfunc
 
-func Test_descructuring_with_lock()
+func Test_destructuring_with_lock()
     const [a, b, c] = [1, 1.1, 'vim']
 
     call assert_fails('let a = 1', 'E741:')