Xext: silence 'warning: no previous prototype' for sync, bigreq and xcmisc.

xcmisc and bigreq don't have their own header so just declare it here to
shut up the compiler.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>

Xext/bigreq.c

@@ -42,6 +42,8 @@ from The Open Group.
 
 static DISPATCH_PROC(ProcBigReqDispatch);
 
+void BigReqExtensionInit(INITARGS);
+
 void
 BigReqExtensionInit(INITARGS)
 {

Xext/syncsrv.h

@@ -173,4 +173,5 @@ extern void SyncDestroySystemCounter(
 );
 extern void InitServertime(void);
 
+extern void SyncExtensionInit(void);
 #endif /* _SYNCSRV_H_ */

Xext/xcmisc.c

@@ -55,6 +55,8 @@ static DISPATCH_PROC(SProcXCMiscGetVersion);
 static DISPATCH_PROC(SProcXCMiscGetXIDList);
 static DISPATCH_PROC(SProcXCMiscGetXIDRange);
 
+void XCMiscExtensionInit(INITARGS);
+
 void
 XCMiscExtensionInit(INITARGS)
 {