GitLab

Switch from host OS detection to target OS detection.
Complain about unknown target OS/architecture.
Disable annoying format string warnings on DJGPP.

Native and cross-compilation now usually just require setting CC.
Examples:
make CC=i586-pc-msdosdjgpp-gcc
make CC="clang -m64"
make CC=i686-w64-mingw32-gcc

Tested for a boatload of native and cross compilation configurations.

There is a new target "make libpayload" in case you don't want to
specify all tools by hand.

Corresponding to flashrom svn r1476.
Signed-off-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net>
Acked-by: David Hendricks <dhendrix@google.com>