patch 8.2.3760: not automatically handling gnome terminal mouse like xterm

Problem:    Not automatically handling gnome terminal mouse like xterm.
Solution:   Default 'ttymouse' to "xterm" and recognize Focus events.
            (issue #9296)
diff --git a/src/os_unix.c b/src/os_unix.c
index f93bc95..32850f3 100644
--- a/src/os_unix.c
+++ b/src/os_unix.c
@@ -2340,6 +2340,7 @@
 	    && (term_is_xterm
 		|| STRNICMP(name, "screen", 6) == 0
 		|| STRNICMP(name, "tmux", 4) == 0
+		|| STRNICMP(name, "gnome", 5) == 0
 		|| STRICMP(name, "st") == 0
 		|| STRNICMP(name, "st-", 3) == 0
 		|| STRNICMP(name, "stterm", 6) == 0));