Fix file open check

fd.ok() returns a bool.  The NOT of that method will auto-cast to
a 0 or 1 as an int, and thus will never equal -1.  So our previous
check was always false.  We remove the int comparison to fix this.

Test: TreeHugger
Change-Id: I20ad5eae79622f680c5516df422a7fef7ff7966b