Fix isValid() condition for libsync tests

Upstream modifications in K3.12 to the sw_sync driver set O_CLOEXEC on
the fd's returned by the SW_SYNC_IOC_CREATE_FENCE ioctl, therefore we
check the return of fcntl() for a non-negative value instead of strictly 0.

Change-Id: If4c82750fcc0aa3a57f243fa2a94691e3150e4a4

libsync/tests/sync_test.cpp

@@ -50,7 +50,7 @@ public:
     bool isValid() const {
         if (m_fdInitialized) {
             int status = fcntl(m_fd, F_GETFD, 0);
-            if (status == 0)
+            if (status >= 0)
                 return true;
             else
                 return false;
@@ -92,7 +92,7 @@ public:
     bool isValid() const {
         if (m_fdInitialized) {
             int status = fcntl(m_fd, F_GETFD, 0);
-            if (status == 0)
+            if (status >= 0)
                 return true;
             else
                 return false;