11927 Log, or optionally panic, on zero-length kmem allocations
Reviewed by: Dan McDonald <danmcd@joyent.com>
Reviewed by: Jason King <jason.brian.king@gmail.com>

*** 4291,4302 ****
          { "allocdby", ":", "given a thread, print its allocated buffers",
                  allocdby },
          { "bufctl", ":[-vh] [-a addr] [-c caller] [-e earliest] [-l latest] "
                  "[-t thd]", "print or filter a bufctl", bufctl, bufctl_help },
          { "freedby", ":", "given a thread, print its freed buffers", freedby },
!         { "kmalog", "?[ fail | slab ]",
!             "display kmem transaction log and stack traces", kmalog },
          { "kmastat", "[-kmg]", "kernel memory allocator stats",
              kmastat },
          { "kmausers", "?[-ef] [cache ...]", "current medium and large users "
                  "of the kmem allocator", kmausers, kmausers_help },
          { "kmem_cache", "?[-n name]",
--- 4291,4303 ----
          { "allocdby", ":", "given a thread, print its allocated buffers",
                  allocdby },
          { "bufctl", ":[-vh] [-a addr] [-c caller] [-e earliest] [-l latest] "
                  "[-t thd]", "print or filter a bufctl", bufctl, bufctl_help },
          { "freedby", ":", "given a thread, print its freed buffers", freedby },
!         { "kmalog", "?[ fail | slab | zerosized ]",
!             "display kmem transaction log and stack traces for specified type",
!             kmalog },
          { "kmastat", "[-kmg]", "kernel memory allocator stats",
              kmastat },
          { "kmausers", "?[-ef] [cache ...]", "current medium and large users "
                  "of the kmem allocator", kmausers, kmausers_help },
          { "kmem_cache", "?[-n name]",