Also add a cross compile script to test always cross
compilation for some well known platforms and architectures
, we support out of box compilation of these platforms even
if we don't make an official release build.
This script is to avoid regressions in this area when we
add platform dependent code.
* Use 0-byte file for bitrot verification of whole-file-bitrot files
Also pass the right checksum information for bitrot verification
* Copy xlMeta info from latest meta except []checksums and []Parts while healing
