sawman: add autoreconf step

sawman needs the autoreconf step added in order for Vicente Olivert
Riera's patch - "sawman: Link using gcc instead of ld"
(8fc5ea00) - to take effect.

Fixes:
  http://autobuild.buildroot.net/results/19b/19bfe0d39e457fd260b73928331721f57555fc84



Signed-off-by: Ryan Barnett <rjbarnet@rockwellcollins.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>