xcursor: fix CVE-2013-2003

The libXcursor fix for CVE-2013-2003 has never been imported into
wlroots, leaving it vulnerable to it.

Changing the argument type to an unsigned type is an effective merge of
Ilja Van Sprundel's commit in libXcursor.

Proof of Concept (compile with address sanitizer):

$ mkdir -p ~/.local/share/icons/poc/cursors
$ base64 -d <<< WGN1chAAAAAAAAAA/////w== > \
    ~/.local/share/icons/poc/cursors/poc
$ echo "seat seat0 xcursor_theme poc 10" > ~/poc-config
$ sway -c ~/poc-config

1 files changed, 1 insertions, 1 deletions

diff --git a/xcursor/xcursor.c b/xcursor/xcursor.c
index 5c4538a2..4415a659 100644
--- a/xcursor/xcursor.c
+++ b/xcursor/xcursor.c
@@ -301,7 +301,7 @@ _XcursorFileHeaderDestroy (XcursorFileHeader *fileHeader)
 }
 
 static XcursorFileHeader *
-_XcursorFileHeaderCreate (int ntoc)
+_XcursorFileHeaderCreate (XcursorUInt ntoc)
 {
     XcursorFileHeader	*fileHeader;