[fpc-pascal] Convert codepages back to UTF8

[Alexey Tor.]

LazUtils.LConvEncoding can convert utf8 to codepage (not many codepages) 
and vice versa.

FPC 3 can convert utf8 to codepage - via SetCodePage(s, codepage, true). 
But how can FPC convert back - codepage to utf8? Does such way exist?

-- 
Regards,
Alexey