Fix clang-tidy issues discoverd by new clang-tidy version

apps/EchoServer.cpp

apps/fsearch/fsearch.cpp

apps/fsearch/fsearch_callback.cpp

emper/Runtime.cpp

emper/io/io.cpp

emper/lib/DebugUtil.cpp

tests/ContextOutOfBoundsTest.cpp

tests/io/SimpleDiskAndNetworkTest.cpp