Make flush explicit

A more in depth explanation of this is here[1], but being explicit
flushing the buffer (using std::flush) captures intent better here,
which we intend a newline, then a flush.  Keeping those as separate
captures the intended behavior.

Tested: Launching bmcweb shows logging statements still function.

[1] https://clang.llvm.org/extra/clang-tidy/checks/performance/avoid-endl.html

Change-Id: I6aa427f4e4134ce30ce552cbfdd5d7be3df56c47
Signed-off-by: Ed Tanous <ed@tanous.net>
diff --git a/http/logging.hpp b/http/logging.hpp
index 781bcfb..0ed4777 100644
--- a/http/logging.hpp
+++ b/http/logging.hpp
@@ -196,7 +196,8 @@
     filename = filename.substr(filename.rfind('/') + 1);
     std::cout << std::format("[{} {}:{}] ", levelString, filename,
                              format.loc.line())
-              << std::vformat(format.str, args) << std::endl;
+              << std::vformat(format.str, args) << '\n'
+              << std::flush;
 }
 } // namespace crow