Call cache_purgevfs() from resume_fs to ensure all cache is purged in
rollback etc.

(cherry picked from commit e5d3293b00a0d71a521f10ccc1153f9a9e826e62)
Allow ZFS to call malloc with size = 0

(cherry picked from commit 339ef384678bdc1e09744cf7b708be25ba74abf4)
Remove the hacked symbols for LOOKUP/MKDIR/SYMLINK as we no longer
require them in ZFS.

(cherry picked from commit e5b9ef42dc82dc4add937d45f53f2fd8445d7d20)