Revision 4875

Prefix all build output file names of files which end up in the build
directory with "build/" for consistency (trivial, sort of).

Also, drop printing of "config.g" input file, we usually only print
generated/output files in the build output.

Finally, rename non-existing COMPRESSFLAG variable to
CBFS_PAYLOAD_COMPRESS_FLAG in a printf line. The build output now says

    PAYLOAD    payload.elf l

for payloads (the "l" specifies LZMA compression).

Signed-off-by: Uwe Hermann <uwe@hermann-uwe.de>
Acked-by: Uwe Hermann <uwe@hermann-uwe.de>