Change the struct member data to int64_t

It also changed in FreeBSD 12 from intptr_t to an int64_T

lib/rb-kqueue/native.rb

@@ -14,20 +14,28 @@ module Native
     # @private
     class KEvent < FFI::Struct
       if FFI::Platform::IS_FREEBSD
+        # The FFI gem incorrectly determines the freebsd version, by ignoring
+        # the decimal place
+        freebsd_version = RbConfig::CONFIG['host_os'].gsub(/[^\d.]/, '').to_f
+
         fields = [
           :ident,  :uintptr_t,
           :filter, :short,
           :flags,  :u_short,
-          :fflags, :u_int,
-          :data,   :intptr_t,
-          :udata,  :pointer ]
-
-        # The FFI gem incorrectly determines the freebsd version, by ignoring
-        # the decimal place
-        freebsd_version = RbConfig::CONFIG['host_os'].gsub(/[^\d.]/, '').to_f
+          :fflags, :u_int ]
 
         if freebsd_version >= 12.0
-          fields.push(:ext, [ :u_int64_t, 4 ])
+          fields.push(
+            :data,  :int64_t,
+            :udata, :pointer,
+            :ext,   [ :u_int64_t, 4 ])
+        else
+          # FreeBSD 11 has no ext member, and uses intptr_t for
+          # data member
+          fields.push(
+            :data,  :intptr_t,
+            :udata, :pointer
+          )
         end
 
         layout(*fields)