[images] Ask blobfs tool to record size information into a file

This passes the --sizes flag to the blobfs tool, which asks it record
information about the size used by each blob to a file. This data can
be picked up by 'fx blobstats' and similar tools for image size
analysis.

Test: CQ
ZX-3303 #comment build rules for --sizes flag

Change-Id: I7b2119594a25f5ad8205c33d3b49bb82983bbf4f
1 file changed