lib/rculist: New RCU-iterator, single-writer doubly-linked list.

rculist allows concurrent lockless list iteration, while a writer may
be modifying the list.  Multiple writers can be supported by using a
mutex in addition to rculist.

First user will be added in a following patch.

Signed-off-by: Jarno Rajahalme <jrajahalme@nicira.com>
Acked-by: Ben Pfaff <blp@nicira.com>
tests/test-classifier: Properly use ovsrcu_postpone.

Following patches add stricter checks of RCU memory management of
rules removed from a classifier.  This patch properly postpones
freeing of 'struct cls_rule's that have been removed from a
classifier.

Also remove all the rules from classifier before destructing it in
test_rule_replacement().

Signed-off-by: Jarno Rajahalme <jrajahalme@nicira.com>
Acked-by: Ben Pfaff <blp@nicira.com>
These changes cause shared libraries to be built by default. In
particular, lib/libopenvwitch.so, lib/libsflow.so,
ofproto/libofproto.so, and ovsdb/libovsdb.so will be built. Original
behavior of building static objects excusively may be accomplished by
providing the --disable-shared argument to configure.

Additionally, versioning is introduced to each of the libraries objects
paving the way for APIs to be built around them. A detailed comment
outlining the rules for changing a version number is provided in
configure.ac. Note that at this time, the version number is set to
1.0.0, no API is specified yet, and there are no requirements to
maintain
any sort of compatibility in any of the libraries.

Signed-off-by: Scott Mann <smann@noironetworks.com>