fixing if typo

Author: jvazquez-r7

modules/auxiliary/scanner/http/symantec_brightmail_logfile.rb

@@ -121,7 +121,7 @@ def download_file(sid, fname)
 		if not res
 			print_error("#{peer} - Unable to download the file. The server timed out.")
 			return
-		if res and res.body.empty?
+		elsif res and res.body.empty?
 			print_error("#{peer} - File not found or empty.")
 			return
 		end