Fix error int64_t was not declared (#4419)
Fix error int64_t was not declared (#4419)

The <cstdint> header should be declared to use int64_t type based on https://www.cplusplus.com/reference/cstdint/ . 
This also fix error when compile on Alpine Linux.
UdjinM6/dash,thelazier/dash,dashpay/dash,UdjinM6/dash,dashpay/dash,UdjinM6/dash,thelazier/dash,thelazier/dash,dashpay/dash,dashpay/dash,UdjinM6/dash,dashpay/dash,thelazier/dash,thelazier/dash,UdjinM6/dash