Fix -E argument; add ifdefs for SDL

src/include/86box/86box.h

@@ -186,6 +186,7 @@ extern int    pit_mode;                     /* (C) force setting PIT mode */
 extern int    fm_driver;                    /* (C) select FM sound driver */
 extern int    hook_enabled;                 /* (C) Keyboard hook is enabled */
 extern int    vmm_disabled;                 /* (G) disable built-in manager */
+extern char   vmm_path_cfg[1024];           /* (G) VMs path (unless -E is used) */
 
 extern char exe_path[2048];     /* path (dir) of executable */
 extern char usr_path[1024];     /* path (dir) of user data */