Under Linux OS there's no need to redefine int64_t as a data type
still including sys/types.h to take care of any missing data types.
The following compilation errors are thrown if int64_t is defined:
Error:(50, 36) error: typedef redefinition with different types
('unsigned long long' vs '__uint64_t' (aka 'unsigned long'))
Error:(51, 37) error: typedef redefinition with different types
('long long' vs '__int64_t' (aka 'long'))
Issue: https://github.com/XProger/OpenLara/issues/67
Signed-off-by: Carlos Santa <santa.cm@gmail.com>