patch 8.2.0894: :mkspell can take very long if the word count is high

Problem:    :mkspell can take very long if the word count is high.
Solution:   Use long to avoid negative numbers.  Increase the limits by 20% if
            the compression did not have effect.
diff --git a/src/version.c b/src/version.c
index fc6d897..e270882 100644
--- a/src/version.c
+++ b/src/version.c
@@ -747,6 +747,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    894,
+/**/
     893,
 /**/
     892,