mke2fs, libext2fs: fix bugs on windows

Added O_BINARY to open output files on windows, otherwise they're
written as text files and have invalid data.

Use '(filename):block_count:block_size' for sparse file name because
windows file name can contain ':', e.g. 'c:\output_file'.

Bug: 23686092

Change-Id: I731c13e5df0be8c831464c431b8949d33438fb24
4 files changed