sandbox: add getopt support

This adds simple command-line parsing to sandbox. The idea is that it
sets up the state with options provided, and this state can then be
queried later, as needed.

New flags are declared with the SB_CMDLINE_OPT_SHORT helper macro,
pointers are automatically gathered up in a special section, and
then the core code takes care of gathering them up and processing
at runtime.  This way there is no central place where we have to
store a list of flags with ifdefs.

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

include/os.h

@@ -27,6 +27,8 @@
 #ifndef __OS_H__
 #define __OS_H__
 
+struct sandbox_state;
+
 /**
  * Access to the OS read() system call
  *
@@ -122,4 +124,16 @@ void os_usleep(unsigned long usec);
  */
 u64 os_get_nsec(void);
 
+/**
+ * Parse arguments and update sandbox state.
+ *
+ * @param state		Sandbox state to update
+ * @param argc		Argument count
+ * @param argv		Argument vector
+ * @return 0 if ok, and program should continue;
+ *	1 if ok, but program should stop;
+ *	-1 on error: program should terminate.
+ */
+int os_parse_args(struct sandbox_state *state, int argc, char *argv[]);
+
 #endif