tinc: disable PIE on ARC

tinc: disable PIE on ARC

Even though ARC gcc understands "-pie" option and attempts to generate
PIE binaries as of today PIE is not really supported for user-space
applications.

So we disable PIE detection if building for ARC.
That fixes http://autobuild.buildroot.net/results/2b1/2b1aa474fc432f3f79b03c4577d68642bb7e0f9c
and also prevents execution of non-supported PIE binary in runtime.

[Thomas: fix indentation.]

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>