support/scripts: add relocate-sdk.sh script for SDK relocation

It will install the script "relocate-sdk.sh" in the HOST_DIR
allowing to adjust the path to the SDK directory in all text
files after it has been moved to a new location.

Signed-off-by: Wolfgang Grandegger <wg@grandegger.com>
[Thomas:
 - Fix shebang to be /bin/sh instead of /bin/bash, suggested by Arnout
 - Use | instead of \ as a separator for sed expressions, suggested by
   Arnout, discussed with Wolfgang and others
 - Remove ./ at the beginning of LOCFILE, suggested by Arnout
 - Fix comment about the path check being made before doing the
   replacement, suggested by Arnout
 - Fix indentation, suggested by Arnout.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>