A random assortment of fixes (#9513)

* Android: Make sure sdcv can find the STL
* DocCache: Be less greedy when serializing to disk, and only do that for the *current* document ;).
* CanvasContext: Explicitly document API quirks.
* Fontlist: Switch the on-disk Persist format to zstd (it's ever so slightly faster).
* Bump base for https://github.com/koreader/koreader-base/pull/1515 (fix #9506)

frontend/document/document.lua

@@ -445,6 +445,7 @@ function Document:renderPage(pageno, rect, zoom, rotation, gamma, render_mode, h
     -- prepare cache item with contained blitbuffer
     tile = TileCacheItem:new{
         persistent = true,
+        doc_path = self.file,
         created_ts = os.time(),
         excerpt = size,
         pageno = pageno,