ptxed: use block decoder

Add new options

  --insn-decoder
  --block-decoder

to select the libipt decoder to be used.  The default is the new block decoder.

Change-Id: I2e21982c51d845eec4302a24120a419a1c2abbce
Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>