patch 8.1.1318: code for text changes is in a "misc" file

Problem:    Code for text changes is in a "misc" file.
Solution:   Move the code to change.c.
diff --git a/src/Make_morph.mak b/src/Make_morph.mak
index a5ce62b..1eb5ff5 100644
--- a/src/Make_morph.mak
+++ b/src/Make_morph.mak
@@ -28,6 +28,7 @@
 	autocmd.c						\
 	blowfish.c						\
 	buffer.c						\
+	change.c						\
 	charset.c						\
 	crypt.c							\
 	crypt_zip.c						\