TileCache: Preserve BlitBuffer's inversion & rotation (#8547)

* TileCache: Preserve BlitBuffer's inversion & rotation

This somehow fell through the cracks for all these years ;).

(We can't simply save the config field directly, because bb.fromstring
always generates an allocated bb, which may not be the case of the
source bb).

* Bump base

https://github.com/koreader/koreader-base/pull/1440

base

@@ -1 +1 @@
-Subproject commit eb1285d2e3e20ecf886695a474cae11e556c3437
+Subproject commit 2e53592573718a59399df1739a92b39cf8d92e2d

frontend/document/tilecacheitem.lua

@@ -24,6 +24,8 @@ function TileCacheItem:totable()
             h = self.bb.h,
             stride = tonumber(self.bb.stride),
             fmt = self.bb:getType(),
+            rotation = self.bb:getRotation(),
+            inverse = self.bb:getInverse(),
             data = Blitbuffer.tostring(self.bb),
         },
     }
@@ -54,7 +56,7 @@ function TileCacheItem:fromtable(t)
     self.excerpt = t.excerpt
     self.created_ts = t.created_ts
     self.persistent = t.persistent
-    self.bb = Blitbuffer.fromstring(t.bb.w, t.bb.h, t.bb.fmt, t.bb.data, t.bb.stride)
+    self.bb = Blitbuffer.fromstring(t.bb.w, t.bb.h, t.bb.fmt, t.bb.data, t.bb.stride, t.bb.rotation, t.bb.inverse)
 end
 
 function TileCacheItem:load(filename)