Reviewers: dev-osl_imageworks.com, osl-dev_googlegroups.com,

Description:
Two small things I noticed while debugging something unrelated.

1) check_nan was off-by one

2) we allocate space for struct params even though they are never used
directly


I also added a bit more information to the check_nan output (including
which point was nan).

Please review this at http://codereview.appspot.com/204077/show

Affected files:
src/liboslexec/exec.cpp
src/liboslexec/oslexec_pvt.h