bump crengine: cache and text fixes, use utf8proc

Bump crengine:
- Ensure text decoration (underline) is continued over word gaps
- Invalidate TOC page numbers on rendering change
- Ensure reproducible cache files when same rendering settings
- LVBlockWriteStream: workaround to exclude fatal error
- Use utf8proc for string uppercase/lowercase/capitalize

Bump base:
Thirdparty: adds utf8proc 2.3.0 (libutf8proc.so.2)
For use by crengine, for now mostly for more complete and
accurate text-transform: uppercase/lowercase/capitalize.

Also revert test tweak (in 27ddd6f) to workaround an issue with
cre cache that should be solved by this crengine bump.

base

@@ -1 +1 @@
-Subproject commit ec2fb48c31995ba00119aeb264c65a4fbdbe688f
+Subproject commit 6b6497871ba269e25ac9b2be69e1c77a106ac4d8

spec/unit/readertoc_spec.lua

@@ -1,23 +1,19 @@
 describe("Readertoc module", function()
-    local DocumentRegistry, Event, ReaderUI, DEBUG
+    local DocumentRegistry, ReaderUI, DEBUG
     local readerui, toc, toc_max_depth, title
 
     setup(function()
         require("commonrequire")
         DocumentRegistry = require("document/documentregistry")
-        Event = require("ui/event")
         ReaderUI = require("apps/reader/readerui")
         DEBUG = require("dbg")
 
         local sample_epub = "spec/front/unit/data/juliet.epub"
-
         readerui = ReaderUI:new{
             document = DocumentRegistry:openDocument(sample_epub),
         }
         -- reset book to first page
         readerui.rolling:onGotoPage(0)
-        readerui.document:setSpaceCondensing(75)
-        readerui:handleEvent(Event:new("ChangeScreenMode", "portrait"))
         toc = readerui.toc
     end)