pttc: add support for ?-padding labels

Ptdump uses ? to mark masked-out portions of an IP.  Allow pttc to
generate the expected output using the convenient label + mask syntax.

Change-Id: Ic85c3c2b1742df1860efe7448a95d1ddbef89c4c
Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>
ptt: test return compression

Add tests covering compressed and uncompressed return after direct and
indirect near calls.

Change-Id: If6e88c55f1ece68635b41503958957fdd3b74871
Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>