I was trying to get a dev environment set up on Linux Mint this weekend and ran into the same problem.  I tracked it down as being due to libclang-3.4-dev being built against a prerelease SVN checkout in saucy (package version 1:3.4~svn183914-1ubuntu1).  There's a newer version of the package that fixes this in trusty (1:3.4-1ubuntu3).  I think we should leave this line alone and recommend not using the broken package.  Users should either upgrade to trusty or downgrade to clang 3.3 or build clang 3.4 from source.