tools/rbd_nbd: build without "using namespace std"

* add "std::" prefix in headers
* add "using" declarations in .cc files.

so we don't rely on "using namespace std" in one or more included
headers.

Signed-off-by: Kefu Chai <kchai@redhat.com>

diff --git a/src/tools/rbd_nbd/rbd-nbd.cc b/src/tools/rbd_nbd/rbd-nbd.cc
index f7231f223fc49d271ab72fb19ad8d3033022b6ae..28686842873f75bb4613db63abdee513932f899a 100644 (file)
--- a/src/tools/rbd_nbd/rbd-nbd.cc
+++ b/src/tools/rbd_nbd/rbd-nbd.cc
@@ -80,6 +80,7 @@
 #undef dout_prefix
 #define dout_prefix *_dout << "rbd-nbd: "
 
+using namespace std;
 namespace fs = std::filesystem;
 
 using boost::endian::big_to_native;