[PATCH] [TargetInfo] Move LinkerInputFile to TargetInfo and rename more specific name

[Shankar Kalpathi Easwaran]

  as I have iterated earlier a simple undefined atom does not work in all cases. with elf it has to be an elfundefinedatom. the linker internal file for elf will undergo more changes to add elfdefined atoms which will make elf linker create another version of the interface. this will end up with a non clean code. I want the interface to be same as what existed with my patch.

http://llvm-reviews.chandlerc.com/D1016