Add user execution permission to get_build_revision.sh in build.xml

[yaojingguo]

Run 'chmod u+x' over get_build_revision.sh in case that this script does
not have user execution permission. It has sometimes happened on
CentOS platforms.

[rangadi]

The patch seems safe. But looks to be redundant. Can you reproduce the issue? May be umask is not set properly?

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}