Fix compilation errors on Windows
Fix compilation errors on Windows

MSVC doesn't support fSpinLock=ATOMIC_FLAG_INIT; in the class definition, nor in the class constructor initializer list

marsupial/cling,karies/cling,perovic/cling,marsupial/cling,root-mirror/cling,karies/cling,perovic/cling,perovic/cling,karies/cling,karies/cling,root-mirror/cling,karies/cling,marsupial/cling,marsupial/cling,root-mirror/cling,marsupial/cling,root-mirror/cling,root-mirror/cling,root-mirror/cling,perovic/cling,perovic/cling,marsupial/cling,karies/cling