Add relro support

Add support for PT_GNU_RELRO. This allows the static linker to
indicate that certain regions of memory should be marked as
"read-only" after dynamic linking is complete.

  * (section 6)

Note that this change has no effect on Android right now, because
we don't compile our code with relro enabled.

Change-Id: I6541f8775367e8558b4388f7d105b1ae6e8f046b
4 files changed