test: : 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>

1 files changed, 1 insertions, 1 deletions

diff --git a/src/test/rgw/test_log_backing.cc b/src/test/rgw/test_log_backing.cc
index c67debb9f59..6c9a1b9e3c0 100644
--- a/src/test/rgw/test_log_backing.cc
+++ b/src/test/rgw/test_log_backing.cc
@@ -189,7 +189,7 @@ TEST_F(LogBacking, TestFIFOEmpty)
 }
 
 TEST(CursorGen, RoundTrip) {
-  const auto pcurs = "fded"sv;
+  const std::string_view pcurs = "fded";
   {
     auto gc = gencursor(0, pcurs);
     ASSERT_EQ(pcurs, gc);