MINOR: ssl: add SSL_SERVER_LOCK label in threads.h

Amaury reported that the commit 3ce6eed ("MEDIUM: ssl: add a rwlock for
SSL server session cache") introduced some warning during compilation:

    include/haproxy/thread.h|411 col 2| warning: enumeration value 'SSL_SERVER_LOCK' not handled in switch [-Wswitch]

This patch fix the issue by adding the right entry in the switch block.

Must be backported where 3ce6eed is backported. (2.4 only for now)
1 file changed