Redundant test

By the time the program execution reaches the test of this condition there is only one possible outcome for the test. The code at the destination of this branch is not dead, either because this condition is always true or because there is at least one other branch that reaches it. Test always evaluates the same
/bench/wtperf/wtperf_misc.c:225: DEADCODE 138754 At condition "rfd != -1", the value of "rfd" must be at least 0.
/bench/wtperf/wtperf_misc.c:205: DEADCODE 138754 Condition "rfd < 0", taking false branch. Now the value of "rfd" is at least 0.
/bench/wtperf/wtperf_misc.c:225: DEADCODE 138754 The condition "rfd != -1" must be true.