add last backwards-compatible version

foobar2000/SDK/filesystem_transacted.h

@@ -38,7 +38,5 @@ public:
 	virtual bool is_our_path( const char * path ) = 0;
 };
 
-// Since 1.5, transacted filesystem is no longer supported 
-// as it adds extra complexity without actually solving any problems.
-// Even Microsoft recommends not to use this API.
-#define FB2K_SUPPORT_TRANSACTED_FILESYSTEM 0
+// Defined but not actually provided for MS Store target - because it plainly doesn't work there
+#define FB2K_SUPPORT_TRANSACTED_FILESYSTEM (!FB2K_TARGET_MICROSOFT_STORE)