00-rootdev.sh: use realpath instead of readlink to resolve symlinks

This may fix Gentoo bug #501226

defaults/initrd.d/00-rootdev.sh

@@ -200,7 +200,7 @@ ensure_initramfs_mounts() {
         dev=$(_get_mount_device "${fs}")
         [ -z "${dev}" ] && continue
         # Resolve it like util-linux mount does
-        [ -L "${dev}" ] && dev=$(readlink "${dev}")
+        [ -L "${dev}" ] && dev=$(realpath "${dev}")
         # In this case, it's probably part of the filesystem
         # and not a mountpoint
         [ -z "${dev}" ] && continue

gen_initramfs.sh

@@ -136,7 +136,7 @@ append_busybox() {
 
     # Set up a few default symlinks
     local default_applets="[ ash sh mount uname ls echo cut cat flock stty"
-    default_applets+=" readlink mountpoint dmesg udhcpc"
+    default_applets+=" readlink realpath mountpoint dmesg udhcpc"
     for i in ${BUSYBOX_APPLETS:-${default_applets}}; do
         rm -f ${TEMP}/initramfs-busybox-temp/bin/$i
         ln -s busybox ${TEMP}/initramfs-busybox-temp/bin/$i ||