arm: Drop linker script when building without PIE

The current section headers generated by bionic are incompatible
with this (interp is in, ctors were dropped, and other tiny changes
related to Elf32_Dyn). But... we don't actually need this to
disable PIE, so drop it entirely instead of writing a new one.

Change-Id: I3b350a9f6251e60bf52114343d190f3d6d83b216
Fixes for Xcode 5 and OSX 10.9.
kernel.mk: Put elf.h into the include path on Darwin builds.

Change-Id: I7069b956965d27caac3b2e4c3cc2e8b4c1da7a82