https://github.com/NixOS/nixpkgs/commit/f216b03d5b01490aadc54e5e9d5e3cb607816262

Origin: https://build.opensuse.org/package/view_file/X11:XOrg/tigervnc/u_xorg-server-1.20.7-ddxInputThreadInit.patch
diff -u -p -r tigervnc-1.10.0.old/unix/xserver/hw/vnc/xvnc.c tigervnc-1.10.0/unix/xserver/hw/vnc/xvnc.c
--- tigervnc-1.10.0.old/unix/xserver/hw/vnc/xvnc.c	2020-01-15 11:19:19.486731848 +0000
+++ tigervnc-1.10.0/unix/xserver/hw/vnc/xvnc.c	2020-01-15 11:37:33.275445409 +0000
@@ -295,6 +295,15 @@ void ddxBeforeReset(void)
 }
 #endif
 
+#if INPUTTHREAD
+/** This function is called in Xserver/os/inputthread.c when starting
+    the input thread. */
+void
+ddxInputThreadInit(void)
+{
+}
+#endif
+
 void ddxUseMsg(void)
 {
     vncPrintBanner();

