[PATCH] Entry point function should never be dead-stripped.

[Shankar Kalpathi Easwaran]

  From the correctness point and to have the implementation clean, we shouldnot be adding things in the deadStripRootSet. Your approach is providing two ways of adding it into the deadStripRoot set which is not clean in my opinion.

  Sorry about the comment earlier, all  atoms seen in the command line may not be part of the deadStripRoot set. I have an example with ELF where the symbols are not part of the deadstrip root set, even if they are symbols seen in the command line.

http://llvm-reviews.chandlerc.com/D1524