Add build and test scripts for the svn-x64-macosx build slave.

[in tools/buildbot/slaves/svn-x64-macosx]
* mkramdisk.sh, rmramdisk.sh, setenv.sh,
  svnclean.sh, svnbuild.sh, svncheck.sh: New files.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1638240 13f79535-47bb-0310-9956-ffa450edef68