ChromeOS untar

This is a tool that is intended to support untarring on SquashFS file
systems. In particular, every time it encounters a hard link, it
will just create a copy of the file.

Usage: cruntar [-jmvpz] archive [dest]

Flags:
        -a      Shortcut for -m -p: preserve owners and file mode.
        -j      The archive is compressed with bzip2.
        -m      Preserve file modes.
        -p      Preserve ownership.
        -v      Print the name of each file as it is being processed.
        -z      The archive is compressed with gzip.

I wrote this after running into problems with untarring the
gcc-arm-eabi-none toolchain. The shared storage in Termux under
ChromeOS doesn't support hard links, so I opted to just make a copy
rather than dealing with links and whatnot.