Only build IPCmode tests on Linux

These tests can only be run on a local Linux daemon, so there's
no need to build them on Windows

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
(cherry picked from commit 84224935ea78d93e21a21c0e1e0aa3e83a5c7853)
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>