Under linux, use the much faster CLOCK_REALTIME_COARSE clock by default (SPDLOG_CLOCK_COARSE is defined in common.h)

coarse clock, short log level

respect user-set compiler name

what if my clang compiler is not clang but clang-3.5?

discard policies on queue overflow

worker warmup callback

Fixed 2 macro redefinition warnings related to WIN32_LEAN_AND_MEAN.