Remove an obsolete patch.

This fixes the following link failure:

ld: error: duplicate symbol: ddxInputThreadInit
>>> defined at xvnc.c
>>>            Xvnc-xvnc.o:(ddxInputThreadInit)
>>> defined at Input.c
>>>            libvnccommon_la-Input.o:(.text+0xDC0) in archive ./.libs/libvnccommon.a
c++: error: linker command failed with exit code 1 (use -v to see invocation)

net/tigervnc-server/files/patch-unix_xserver_hw_vnc_xvnc.c

@@ -1,18 +0,0 @@
---- unix/xserver/hw/vnc/xvnc.c.orig	2019-12-20 07:02:02 UTC
-+++ unix/xserver/hw/vnc/xvnc.c
-@@ -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();