linux: Initial support for running Klipper in a Linux real-time process

Add support for compiling the Klipper micro-controller code as a
real-time process capable of running on standard Linux systems.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

src/linux/internal.h

@@ -0,0 +1,17 @@
+#ifndef __LINUX_INTERNAL_H
+#define __LINUX_INTERNAL_H
+// Local definitions for micro-controllers running on linux
+
+#include <time.h> // struct timespec
+
+// console.c
+int console_setup(char *name);
+void console_sleep(struct timespec ts);
+
+// timer.c
+int timer_check_periodic(struct timespec *ts);
+
+// watchdog.c
+int watchdog_setup(void);
+
+#endif // internal.h