* Don't pass empty arguments to ExecuteAndWait because it can cause the

* Don't pass empty arguments to ExecuteAndWait because it can cause the
  sub-tool to start reading its standard input instead of the specified
  input.
* Clean up ouput of path names on error.
* Extend GetPathForLinkageItem to always search the LibraryPaths and thus
  make it suitable for an interface function (required by llvmc.cpp).
* Implement support for language-specific default library paths.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@18188 91177308-0d34-0410-b5e6-96231b3b80d8