Change the order that the DarwinKernel DynamicLoader plugin uses

to search for kexts on the local system -- the ModuleList FindModule()
method is the best first attempt, only call
Symbols::DownloadObjectAndSymbolFile() if that has failed and this
is the kernel binary which really needs to have its symbols located.

<rdar://problem/13241893> 

llvm-svn: 175495