[SRU Xenial] LP#1574982 -- build fixes for PIE compilers

[Andy Whitcroft]

When the kernel is compiled with a compiler with Position Independant
Executable (PIE) enabled by default we end up with a serious disturbance in
the force.  The kernel fails to build in any number of places as it assumes
it can enable PIC only (which it cannot when PIE is already enabled).
Worse this bleeds over into any external module builds using the Makefiles
in the headers, with those completly failing to build.

We wish to SRU this into Xenial (where is should be a 100% no-op as PIE
is present but disabled by default) as we are still copying these
kernels forward into Yakkety.

Proposing for SRU to Xenial.

-apw