patch 8.1.0998: getcurpos() unexpectedly changes "curswant"

Problem:    getcurpos() unexpectedly changes "curswant".
Solution:   Save and restore "curswant". (closes #4069)
diff --git a/src/version.c b/src/version.c
index 539a1e1..e57b576 100644
--- a/src/version.c
+++ b/src/version.c
@@ -780,6 +780,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    998,
+/**/
     997,
 /**/
     996,