enable PIE for dynamically linked executables

Compile all programs on Android with -fPIE and -pie. This enables
PIE (Position Independent Executables), which helps protect Android
applications from exploitation due to memory management bugs.

Stop using the armelf.x linker script. This script hard codes the
load address of the executable, defeating the position independence
PIE requires.

Note: PIE *static* executables are not supported at this time and
require additional linker changes.

Bug: 5323301
Change-Id: Ieafcc9c4f142495847e163881889d371a59d0878
stop using a custom linker script for static executables.

This is causing problems with making the linker relocatable.

Change-Id: I53e37fba52eabd3145130712d6e9bff074aed493

Conflicts:
	core/combo/TARGET_linux-arm.mk