options: make --fullscreen not a global option

This was disabled in 4ea60a3 and 70c455a, when all options were still
forced file local, and resetting fullscreen was annoyingly reset when
switching to the next file. mpv keeps all options by default, so this
isn't needed anymore.

core/cfg-mplayer.h

@@ -594,8 +594,8 @@ const m_option_t mplayer_opts[]={
     // video mode switching: (x11,xv,dga)
     OPT_MAKE_FLAGS("vm", vidmode, 0),
     // start in fullscreen mode:
-    OPT_MAKE_FLAGS("fullscreen", fullscreen, CONF_GLOBAL),
-    OPT_MAKE_FLAGS("fs", fullscreen, CONF_GLOBAL),
+    OPT_MAKE_FLAGS("fullscreen", fullscreen, 0),
+    OPT_MAKE_FLAGS("fs", fullscreen, 0),
     // set fullscreen switch method (workaround for buggy WMs)
     {"fsmode-dontuse", &vo_fsmode, CONF_TYPE_INT, CONF_RANGE, 0, 31, NULL},
     // set bpp (x11+vm)