Finished adding untested bare functionality vfs

Finished adding untested shm syscalls.
Finished adding untested l4 send/recv helpers

Everything compiles. Now going to fix lots of bugs ;-)

tasks/fs0/src/bdev.c

@@ -0,0 +1,14 @@
+/*
+ * This is just to allocate some memory as a block device.
+ */
+#include <l4/macros.h>
+
+extern char _start_bdev[];
+extern char _end_bdev[];
+
+__attribute__((section(".data.memfs"))) char blockdevice[SZ_16MB];
+
+void *vfs_rootdev_open(void)
+{
+	return (void *)_start_bdev;
+}