[all] use explicit void parameter lists

This makes it a compile-time error to call a function that semantically
takes no parameters with a nonzero number of arguments.

Previously, such code would still compile, but risk blowing up the stack
if a compiler chose to use something other than caller-cleanup calling
conventions.

common/src/platform/linux/ivshmem.c

@@ -82,7 +82,7 @@ static StringList ivshmemDeviceGetValues(struct Option * option)
   return sl;
 }
 
-void ivshmemOptionsInit()
+void ivshmemOptionsInit(void)
 {
   struct Option options[] =
   {