[libcxx] r220463 - Add -ldl to libc++ tests when sanitizers are used.

[Joerg Sonnenberger]

On Thu, Oct 23, 2014 at 02:54:15AM -0000, Eric Fiselier wrote:
> Author: ericwf
> Date: Wed Oct 22 21:54:15 2014
> New Revision: 220463
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=220463&view=rev
> Log:
> Add -ldl to libc++ tests when sanitizers are used.
> 
> Clang 3.6 no longer links the sanitizer runtime library dependancies when
> -nodefaultlibs is used. This patch manually links in a missing dependancy.

Please check for Linux explicitly. Many platforms don't have libdl.

Joerg