patch 8.0.0793: using wrong terminal name for terminal window

Problem:    Using wrong terminal name for terminal window.
Solution:   When 'term' starts with "xterm" use it for $TERM in a terminal
            window.
diff --git a/src/version.c b/src/version.c
index 3b45c94..5fc0dbf 100644
--- a/src/version.c
+++ b/src/version.c
@@ -770,6 +770,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    793,
+/**/
     792,
 /**/
     791,