[PECOFF] Allocate storage for .drective in the reader to avoid multiple calls of allocateString()

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@189881 91177308-0d34-0410-b5e6-96231b3b80d8
Recognize -rpath-link option and add arguments to ELFLinkingContext.


git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@189883 91177308-0d34-0410-b5e6-96231b3b80d8
[lld][Driver] The driver was creating linker inputs twice

Also add a llvm_unreachable call so that the linker will trip on unhandled
inputElement types.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@189887 91177308-0d34-0410-b5e6-96231b3b80d8