Issue 286: --disable-coverage drops "-pthread" option

-pthread was added as part of setting up the gcov options
alloc loop now attempts an item_lock

Fixes a few issues with a restructuring... I think -M was broken before,
should be fixed now. It had a refcount leak.

Now walks up to five items from the bottom in case of the bottomost items
being item_locked, or refcount locked. Helps avoid excessive OOM errors for
some oddball cases. Those happen more often if you're hammering on a handful
of pages in a very large class size (100k+)

The hash item lock ensures that if we're holding that lock, no other thread
can be incrementing the refcount lock at that time. It will mean more in
future patches.

slab rebalancer gets a similar update.
item locks now lock hash table buckets

expansion requires switching to a global lock temporarily, so all buckets have
a covered read lock.

slab rebalancer is paused during hash table expansion.

internal item "trylocks" are always issued, and tracked as the hash power
variable can change out from under it.
remove global stats lock from item allocation

This doesn't reduce mutex contention much, if at all, for the global stats
lock, but it does remove a handful of instructions from the alloc hot path,
which is always worth doing.

Previous commits possibly added a handful of instructions for the loop and for
the bucket readlock trylock, but this is still faster than .14 for writes
overall.
README.md was missing from dist tarball
don't wait on condition without holding the lock

freebsd9 is the only platform that apparently cares about this.
Add some mild thread documentation

since reading the code is probably incredibly confusing now.
fix enable-sasl-pwdb

* using --enable-sasl-pwdb will make the compile fail with:

sasl_defs.c:148:4: error: initialization from incompatible pointer type [-Werror]
This adds the "shutdown" command to the server. This allows for better
automation (at least,... I find that it makes for better automation).
Merge pull request #22 from gabriel-samfira/master

Compile fails using enable-sasl-pwdb
Merge pull request #26 from trondn/brians-shutdown

This adds the "shutdown" command to the server. This allows for better
Fix make maintainer-clean
add aclocal 1.12 in autogen.sh
Don't truncate maxbytes stat from 'stats settings'

Fixes issue 319
Close connection on update_event error for new cmd

Issue 261. If an update_event fails for case conn_new_cmd but no
more events happen on this socket, conn_closing will never be
processed.

Not sure if it's possible for this to happen, but it could
theoretically leak refcounts.
Create memcached pid file atomically using rename.

This change avoids a race condition where another application (e.g., testapp)
can read the memcached pid file after memcached opens it, but before
memcached writes the pid. It now writes the pid into a temporary file and then
renames that file to the correct pid file name. This way the pid file can not
exist without containing the correct value.
Fix segfault on specially crafted packet.
Make tail leak expiry time configurable
Some tail_repair_time adjustments

fix t/binary.t test.
Default of 3 hours is super overkill. 1 hour is still way too much but within
realm of reason.
Bail if someone sets it really low (10s or negative)
Issue 293: Remove unused condition variable