remove offset from GetTimeMicros()
remove offset from GetTimeMicros()

GetTimeMicros() is used to measure time, accounting offset can lead to imprecisions
navcoindev/navcoin-core,navcoindev/navcoin-core,navcoindev/navcoin-core,navcoindev/navcoin-core,navcoindev/navcoin-core,navcoindev/navcoin-core