Fix ziplist test for pop()

The previous test wasn't returning the new ziplist, so the test
was invalid.  Now the test works properly.
Cleanup ziplist valgrind warnings

Valgrind can't detect 'memset' initializes things, so let's
statically initialize them to remove some unnecessary warnings.
Fix three simple clang analyzer warnings
Add quicklist implementation

This replaces individual ziplist vs. linkedlist representations
for Redis list operations.
Remove config option list-max-ziplist-value

As with all config option removals, this will stop Redis
from loading any config file with that old directive.

Maybe we should allow Redis to ignore invalid directives instead
of halting and refusing to load a config file with unknown settings?