MINOR: stats: report SSL key computations per second

It's commonly needed to know how many SSL asymmetric keys are computed
per second on either side (frontend or backend), and to know the SSL
session reuse ratio. Now we compute these values and report them in
"show info".
MINOR: stats: add counters for SSL cache lookups and misses

One important aspect of SSL performance tuning is the cache size,
but there's no metric to know whether it's large enough or not. This
commit introduces two counters, one for the cache lookups and another
one for cache misses. These counters are reported on "show info" on
the stats socket. This way, it suffices to see the cache misses
counter constantly grow to know that a larger cache could possibly
help.
[RELEASE] Released version 1.5-dev26

Released version 1.5-dev26 with the following main changes :
    - BUG/MEDIUM: polling: fix possible CPU hogging of worker processes after receiving SIGUSR1.
    - BUG/MINOR: stats: fix a typo on a closing tag for a server tracking another one
    - OPTIM: stats: avoid the calculation of a useless link on tracking servers in maintenance
    - MINOR: fix a few memory usage errors
    - CONTRIB: halog: Filter input lines by date and time through timestamp
    - MINOR: ssl: SSL_CTX_set_options() and SSL_CTX_set_mode() take a long, not an int
    - BUG/MEDIUM: regex: fix risk of buffer overrun in exp_replace()
    - MINOR: acl: set "str" as default match for strings
    - DOC: Add some precisions about acl default matching method
    - MEDIUM: acl: strenghten the option parser to report invalid options
    - BUG/MEDIUM: config: a stats-less config crashes in 1.5-dev25
    - BUG/MINOR: checks: tcp-check must not stop on '\0' for binary checks
    - MINOR: stats: improve alignment of color codes to save one line of header
    - MINOR: checks: simplify and improve reporting of state changes when using log-health-checks
    - MINOR: server: remove the SRV_DRAIN flag which can always be deduced
    - MINOR: server: use functions to detect state changes and to update them
    - MINOR: server: create srv_was_usable() from srv_is_usable() and use a pointer
    - BUG/MINOR: stats: do not report "100%" in the thottle column when server is draining
    - BUG/MAJOR: config: don't free valid regex memory
    - BUG/MEDIUM: session: don't clear CF_READ_NOEXP if analysers are not called
    - BUG/MINOR: stats: tracking servers may incorrectly report an inherited DRAIN status
    - MEDIUM: proxy: make timeout parser a bit stricter
    - REORG/MEDIUM: server: split server state and flags in two different variables
    - REORG/MEDIUM: server: move the maintenance bits out of the server state
    - MAJOR: server: use states instead of flags to store the server state
    - REORG: checks: put the functions in the appropriate files !
    - MEDIUM: server: properly support and propagate the maintenance status
    - MEDIUM: server: allow multi-level server tracking
    - CLEANUP: checks: rename the server_status_printf function
    - MEDIUM: checks: simplify server up/down/nolb transitions
    - MAJOR: checks: move health checks changes to set_server_check_status()
    - MINOR: server: make the status reporting function support a reason
    - MINOR: checks: simplify health check reporting functions
    - MINOR: server: implement srv_set_stopped()
    - MINOR: server: implement srv_set_running()
    - MINOR: server: implement srv_set_stopping()
    - MEDIUM: checks: simplify failure notification using srv_set_stopped()
    - MEDIUM: checks: simplify success notification using srv_set_running()
    - MEDIUM: checks: simplify stopping mode notification using srv_set_stopping()
    - MEDIUM: stats: report a server's own state instead of the tracked one's
    - MINOR: server: make use of srv_is_usable() instead of checking eweight
    - MAJOR: checks: add support for a new "drain" administrative mode
    - MINOR: stats: use the admin flags for soft enable/disable/stop/start on the web page
    - MEDIUM: stats: introduce new actions to simplify admin status management
    - MINOR: cli: introduce a new "set server" command
    - MINOR: stats: report a distinct output for DOWN caused by agent
    - MINOR: checks: support specific check reporting for the agent
    - MINOR: checks: support a neutral check result
    - BUG/MINOR: cli: "agent" was missing from the "enable"/"disable" help message
    - MEDIUM: cli: add support for enabling/disabling health checks.
    - MEDIUM: stats: report down caused by agent prior to reporting up
    - MAJOR: agent: rework the response processing and support additional actions
    - MINOR: stats: improve the stats web page to support more actions
    - CONTRIB: halog: avoid calling time/localtime/mktime for each line
    - DOC: document the workarouds for Google Chrome's bogus pre-connect
    - MINOR: stats: report SSL key computations per second
    - MINOR: stats: add counters for SSL cache lookups and misses
BUILD: don't use type "uint" which is not portable

Dmitry Sivachenko reported that "uint" doesn't build on FreeBSD 10.
On Linux it's defined in sys/types.h and indicated as "old". Just
get rid of the very few occurrences.
Merge remote-tracking branch 'upstream2/master'