patch 9.0.0828: various typos

Problem:    Various typos.
Solution:   Correct typos. (closes #11432)
diff --git a/src/spell.h b/src/spell.h
index a085b0b..be11c9f 100644
--- a/src/spell.h
+++ b/src/spell.h
@@ -17,10 +17,10 @@
 # define SPELL_PRINTTREE
 #endif
 
-// Use SPELL_COMPRESS_ALLWAYS for debugging: compress the word tree after
+// Use SPELL_COMPRESS_ALWAYS for debugging: compress the word tree after
 // adding a word.  Only use it for small word lists!
 #if 0
-# define SPELL_COMPRESS_ALLWAYS
+# define SPELL_COMPRESS_ALWAYS
 #endif
 
 // Use DEBUG_TRIEWALK to print the changes made in suggest_trie_walk() for a