deeply nested PKGLIBDIR causes failure

[aanderse]

my PKGLIBDIR is something like /nix/store/j2kh1sb5iyrsy7dj2inwpw83n3mb40rz-initviz-1.0.0-rc1/lib/bootchart and is on a read-only filesystem - this is problematic for the following code:

	/* we need our tmpfs to look like this file-system,
	   so we can chroot into it if necessary */
	mkdir(TMPFS_PATH EARLY_PREFIX, 0777);
	mkdir(TMPFS_PATH EARLY_PREFIX LIBDIR, 0777);
	mkdir(TMPFS_PATH PKGLIBDIR, 0777);
	if (symlink("../..", TMPFS_PATH TMPFS_PATH)) {
		if (errno != EEXIST) {
			log("bootchart-collector failed to create a chroot at "
			    TMPFS_PATH TMPFS_PATH " error '%s'\n", strerror(errno));
			return 1;
		}
	}

i wrote a hacky patch to work around this for now, but i was hoping for a better solution...

additional information: i'm running bootchartd from stage 2 onward, not in my initramfs at all... so i don't specifically need any of this tmpfs stuff at the moment, which is what my hacky patch is fine