Tweak svn-x64-osx scripts to work on older OS versions.

[in tools/buildbot/slaves/svn-x64-macosx]
* mkramdisk.sh: Strip whitespace from teh output of hdiutil.
* setenv.sh: Export the LIBTOOL_CONFIG variable.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1638316 13f79535-47bb-0310-9956-ffa450edef68