patch 9.0.1614: strlen() called too often for :spellrepall

Problem:    strlen() called too often for :spellrepall.
Solution:   Store the result in a variable. (closes #12497)
diff --git a/src/testdir/test_spell.vim b/src/testdir/test_spell.vim
index a42d4c7..3f7b028 100644
--- a/src/testdir/test_spell.vim
+++ b/src/testdir/test_spell.vim
@@ -281,7 +281,7 @@
   set spell& spelllang& dictionary& ignorecase&
 endfunc
 
-func Test_spellreall()
+func Test_spellrepall()
   new
   set spell
   call assert_fails('spellrepall', 'E752:')