Add PROT_* constants not found on windows.

#define _BACKTRACE_BACKTRACE_MAP_H

#include <stdint.h>

#ifdef USE_MINGW

// MINGW does not define these constants.

#define PROT_NONE 0

#define PROT_READ 0x1

#define PROT_WRITE 0x2

#define PROT_EXEC 0x4

#else

#include <sys/mman.h>

#endif

#include <string>

#include <vector>