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

[Shankar Kalpathi Easwaran]

  The entry symbol should have the same effect as a undefined symbol. For example :-

  $ ld --entry=strcpy /usr/lib/libc.a -t
  ld: mode elf_x86_64
  (/usr/lib/libc.a)strcpy.o
  (/usr/lib/libc.a)init-arch.o

  It should be added to the resolver like how undefined symbols are added.

  On a side note, I think all the symbols that are specified in the command line should be part of the deadStripRoot set, that they should not be removed.

http://llvm-reviews.chandlerc.com/D1366