tests: Resolve Coverity RESOURCE_LEAK

The 'lib' handle will be leaked if 'dlsym' condition fails.
So close the handle before return.

Signed-off-by: Wang Rui <moon.wangrui@huawei.com>

tests/shunloadtest.c

@@ -114,6 +114,7 @@ int main(int argc ATTRIBUTE_UNUSED, char **argv)
     }
     if (!(startup = dlsym(lib, "shunloadStart"))) {
         fprintf(stderr, "Cannot find shunloadStart %s\n", dlerror());
+        dlclose(lib);
         return 1;
     }