debug: only do getpid() if we have to

Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/debug.c b/debug.c
index 5e98063..ecee8e3 100644
--- a/debug.c
+++ b/debug.c
@@ -11,9 +11,8 @@
 
 	assert(type < FD_DEBUG_MAX);
 
-	pid = getpid();
 	if (fio_debug_jobp && *fio_debug_jobp != -1U
-	    && pid != *fio_debug_jobp)
+	    && (pid = getpid() != *fio_debug_jobp))
 		return;
 
 	log_local("%-8s ", debug_levels[type].name);