Support lzma images with unset file size

The lzma compression tool stores the size of the uncompressed file in
the header of the lzma output file. However, if it reads its input data
over stdin, it just stores 0xFFFFFFFF as the file size meaning the file
size is unknown.

The Linux kernel makefiles use lzma in the latter mode where we end up
with an lzma file that does not have the file size stored in the header.

This change is similar to the upstream commit

Change-Id: I17993c22afb2b264673f2f5948bd029ff8ad54ff
1 file changed