hammer - Allow userland programs to access hammer.h definitions

Expose hammer.h to userland, programs like fstat(1) might need some
of the structs (struct hammer_inode).
fstat(1) - Add support for HAMMER filesystem.

- Also use %u for printing major/minor to avoid overflows.
ntfs - Expose NTFS structures to userland.
fstat(1) - Add support for NTFS filesystem.