patch 9.0.0997: Coverity warns for dead code

Problem:    Coverity warns for dead code.
Solution:   Don't use ASCII_ISUPPER() for a negative value.
diff --git a/src/version.c b/src/version.c
index 8ccf7d2..682beb0 100644
--- a/src/version.c
+++ b/src/version.c
@@ -696,6 +696,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    997,
+/**/
     996,
 /**/
     995,