In preparation for ASLR [1] support add WITH_PIE to support building with -fPIE

This is currently an opt-in flag. Once ASLR support is ready and stable it
should changed to opt-out and be enabled by default along with ASLR.

Mark known build failures as NO_PIE for now.

The only known runtime failure was rtld.

[1] http://www.bsdcan.org/2014/schedule/events/452.en.html
Submitted by:		Shawn Webb <lattera@gmail.com>
Discussed between:	des, imp, Shawn Webb