Fixed the ability to load multiple __LINKEDIT segments at the same address for...

Fixed the ability to load multiple __LINKEDIT segments at the same address for darwin shared cache entries. Now when registering the load address of a section, the DynamicLoader objects can specify if they should warn or not. This will fix the ability to load the nlist entries for shared libraries in the darwin shared caches when no on disk representation is available for a shared library.

llvm-svn: 154860