Don't call strtok twice if it failed the first time.

diff --git a/msdos/dosconf.c b/msdos/dosconf.c
index 37e4d8a..0e7ee44 100644
--- a/msdos/dosconf.c
+++ b/msdos/dosconf.c
@@ -421,9 +421,8 @@
     int ret = 1;
 
     PROFILE_GetWineIniString( "wine", "config.sys", "", buffer, sizeof(buffer) );
-    filename = strtok(buffer, ",");
+    if (!(filename = strtok(buffer, ","))) return ret;
     menuname = strtok(NULL,   ",");
-    if (!filename) return ret;
 
     DOSFS_GetFullName(filename, FALSE, &fullname);
     if (menuname) menu_default = strdup(menuname);