Add missing stdlib.h, needed for atoi

Change-Id: I859db3be12c24fc4544dc3780e5fdf5c598412d8
Reviewed-on: https://swiftshader-review.googlesource.com/3970
Reviewed-by: Nicolas Capens <capn@google.com>
Tested-by: Greg Hartman <ghartman@google.com>
1 file changed