Fixes for libraries not supporting wide character strings: correct existing V2 workarounds (thanks to John Maddock), V3 library components null compile if no support, #error earlier and in more files if using V3 with unsupported library.

[SVN r64623]

libs/filesystem

@@ -1 +1 @@
-Subproject commit 2e466d3587a8bc9c58fce757e73b674e6637be00
+Subproject commit 91b24db22cd02045d9013b44a4b264df8e8c4062