The state exists through the life of U-Boot. It can be adjusted by command
line options and perhaps later through a config file.  It is available to
U-Boot through state_...() calls (within sandbox code).

The primary purpose of this is to contain the "hardware" state.  It should
only be used by sandbox internal code.

Signed-off-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>

U-boot itself generally builds with -nostdinc.  This is because the
bootloader needs to be completely standalone.  In the sandbox arch
though, we need a little bit of code to glue the u-boot world to the
host operating system, and we need to be able to access the host
libc's headers in order to do so.

Currently, we're using -I/usr/include to workaround the global
-nostdinc, but that doesn't work for everyone and for all headers.
Instead, let's filter out -nostdinc when building the os.c code.

Without this patch, some distros hit errors such as:
---8<---
In file included from /usr/include/fcntl.h:27:0,
                 from os.c:22:
/usr/include/features.h:323:26: fatal error:
     bits/predefs.h: No such file or directory
--->8---

Signed-off-by: Andreas Bießmann <biessmann@corscience.de>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>

Add a main program so that we can run U-Boot.

Signed-off-by: Simon Glass <sjg@chromium.org>

We want to keep all OS-dependent code in once place, with a simple interface
to U-Boot. For now, this is that place.

Signed-off-by: Simon Glass <sjg@chromium.org>

This is an initial implementation with all functions defined but not working.

The lds file is very simple since we can mostly rely on the linker defaults.

Signed-off-by: Simon Glass <sjg@chromium.org>