Add build.xml to .gitattributes/export-ignore

Like other testing files, build.xml is useless for public distribution
Merge branch 'hotfix/4480'

Close #4480
Fixes #4445
Merge pull request #4494 from Slamdunk/patch-1

Add build.xml to .gitattributes/export-ignore
Merge branch 'hotfix/4494' into develop

Forward port #4494