patch 8.1.1616: build failure with gcc on Amiga

Problem:    Build failure with gcc on Amiga.
Solution:   Add missing header includes. (Ola Söder, closes #4603)
diff --git a/src/version.c b/src/version.c
index ec541b4..d05b82e 100644
--- a/src/version.c
+++ b/src/version.c
@@ -778,6 +778,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1616,
+/**/
     1615,
 /**/
     1614,