Modify relative paths of lib, elements for packaging

(Based on review https://review.openstack.org/#/c/36009)

Scripts test for existence of ../share/diskimage-builder and
fall-back to ../ if not found. This allows scripts to run unmodified
from a packaged installation or a local archive/repository.

Change-Id: I0cf4c1fdb8e42ec284c56860cb15818632b93b9e

bin/disk-image-create

@@ -27,7 +27,13 @@ export DIB_ENV=$(export)
 
 SCRIPTNAME=$(basename $0)
 SCRIPT_HOME=$(dirname $0)
-export _LIB=$(dirname $0)/../lib
+if [ -d $SCRIPT_HOME/../share/diskimage-builder ]
+then
+    export _PREFIX=$SCRIPT_HOME/../share/diskimage-builder
+else
+    export _PREFIX=$SCRIPT_HOME/..
+fi
+export _LIB=$_PREFIX/lib
 source $_LIB/die
 
 IS_RAMDISK=0

bin/disk-image-get-kernel

@@ -18,7 +18,14 @@
 set -e
 
 SCRIPTNAME=$(basename $0)
-export _LIB=$(dirname $0)/../lib
+SCRIPT_HOME=$(dirname $0)
+if [ -d $SCRIPT_HOME/../share/diskimage-builder ]
+then
+    export _PREFIX=$SCRIPT_HOME/../share/diskimage-builder
+else
+    export _PREFIX=$SCRIPT_HOME/..
+fi
+export _LIB=$_PREFIX/lib
 source $_LIB/die
 
 function show_options () {

lib/common-defaults

@@ -36,7 +36,7 @@ export ARCH
 export DIB_NO_TMPFS=${DIB_NO_TMPFS:-0}
 # Set via the CLI normally.
 # IMAGE_ELEMENT=
-_BASE_ELEMENT_DIR=$(dirname $0)/../elements
+_BASE_ELEMENT_DIR=$_PREFIX/elements
 ELEMENTS_PATH=${ELEMENTS_PATH:+"$ELEMENTS_PATH:$_BASE_ELEMENT_DIR"}
 export ELEMENTS_PATH=${ELEMENTS_PATH:-$_BASE_ELEMENT_DIR}
 export DIB_OFFLINE=${DIB_OFFLINE:-''}