Fix emacsclient check for term.el buffer (Bug#21041)

* lib-src/emacsclient.c (find_tty): Check for any TERM value with
prefix of "eterm", not just "eterm" itself.  Also check for ",term:"
in INSIDE_EMACS value.

lib-src/emacsclient.c

@@ -1114,7 +1114,9 @@ find_tty (const char **tty_type, const char **tty_name, int noabort)
 	}
     }
 
-  if (strcmp (type, "eterm") == 0)
+  const char *inside_emacs = egetenv ("INSIDE_EMACS");
+  if (inside_emacs && strstr (inside_emacs, ",term:")
+      && strprefix ("eterm", type))
     {
       if (noabort)
 	return 0;