[fb] Create fb driver

Create a new framebuffer driver. Also hackily passing frame buffer size
in the list of init handles to all processes and mapping the framebuffer
into all processes. Changed bootloader passing frame buffer as a module
to its own struct.

src/drivers/fb/main.cpp

@@ -0,0 +1,41 @@
+#include <stdint.h>
+#include <stdlib.h>
+
+#include "j6/types.h"
+#include "j6/errors.h"
+#include "j6/signals.h"
+
+#include <j6libc/syscalls.h>
+
+extern "C" {
+	void _init_libc(j6_process_init *);
+	int main(int, const char **);
+}
+
+j6_handle_t sys = j6_handle_invalid;
+size_t size = 0;
+
+void
+_init_libc(j6_process_init *init)
+{
+	sys = init->handles[0];
+	size = reinterpret_cast<size_t>(init->handles[1]);
+}
+
+int
+main(int argc, const char **argv)
+{
+	_syscall_system_log("fb driver starting");
+
+	if (size == 0)
+		return 1;
+
+	uint32_t *fb = reinterpret_cast<uint32_t*>(0x100000000);
+	for (size_t i=0; i < size/4; ++i) {
+		fb[i] = 0xff;
+	}
+
+	_syscall_system_log("fb driver done, exiting");
+	return 0;
+}
+