libpuffs: clean up, unbreak

- move MINIX3-specific files into minix/lib/libpuffs;
- resynchronize the remaining files with NetBSD code;
- remove a few unnecessary changes;
- put remaining MINIX3-spe

libpuffs: clean up, unbreak

- move MINIX3-specific files into minix/lib/libpuffs;
- resynchronize the remaining files with NetBSD code;
- remove a few unnecessary changes;
- put remaining MINIX3-specific changes in __minix blocks;
- sort out the source files being linked at all.

The result is that libpuffs now successfully links against FUSE
file system programs again. It can successfully mount, perform
some of the most basic operations, and unmount the file system.

Change-Id: Ieac220f7ad8c4d1fa293abda81967e8045be0bb4

show more ...