[3736] Corrected the suppression in the d2_udp_unittest.

src/lib/dhcpsrv/tests/d2_udp_unittest.cc

@@ -115,7 +115,10 @@ public:
 
         // cppcheck-suppress redundantAssignment
         int select_fd = -1;
-        ASSERT_NO_THROW(select_fd = getSelectFd());
+        ASSERT_NO_THROW(
+            // cppcheck-suppress redundantAssignment
+            select_fd = getSelectFd()
+        );
 
         FD_SET(select_fd,  &read_fds);
         maxfd = select_fd;