message: Handle moving files across partitions on macOS
diff: #include <vcpkg/base/system.process.h>
  #include <vcpkg/base/util.h>
  -#if defined(__linux__)
  +#if defined(__linux__) || defined(__APPLE__)
  #include <fcntl.h>
  -#include <sys/sendfile.h>
  #include <sys/stat.h>
  #include <sys/types.h>
  #include <unistd.h>
  +#include <string.h>
  +#endif
  +#if defined(__linux__)
  +#include <sys/sendfile.h>
  +#elif defined(__APPLE__)
  +#include <copyfile.h>
  #endif
  namespace vcpkg::Files
  @@ -166,7 +171,7 @@ namespace vcpkg::Files
  std::error_code& ec) override
  {
  this->rename(oldpath, newpath, ec);
  -#if defined(__linux__)
  +#if defined(__linux__) || defined(__APPLE__)
  if (ec)
  {
  auto dst = newpath;
  @@ -182,13 +187,25 @@ namespace vcpkg::Files
  return;
  }
  +#if defined(__linux__)
  off_t bytes = 0;
  struct stat info = {0};
  fstat(i_fd, &info);
  auto written_bytes = sendfile(o_fd, i_fd, &bytes, info.st_size);
  +#elif defined(__APPLE__)
  + auto written_bytes = fcopyfile(i_fd, o_fd, 0, COPYFILE_ALL);
  +#endif
  + if (written_bytes == -1)
  + {
  + ec.assign(errno, std::generic_category());
  + close(i_fd);
  + close(o_fd);
  +
  + return;
  + }
  +
  close(i_fd);
  close(o_fd);
  - if (written_bytes == -1) return;
  this->rename(dst, newpath, ec);
  if (ec) return;
  