<sys/mman.h> not found

I try to port the Arduino Project SoftRF GitHub - lyusupov/SoftRF: Multi-functional, compatible DIY general aviation proximity awareness system to a PlatformIO Project.
Under the Arduino IDE the application can be compiled.
Under PlatformIO the <sys/mman.h> headerfile can not be found.
As device i use a TTGO T-Beam.
Any advice?

ThX Tom

Did you do any changes to Arduino core?