remove syncrepl stuff from Operation struct

Still needs: error checking, queuing results when refresh is in progress

buddy allocator for sl_malloc. Configurable at thread heap creation time. Need optimization for higher perf.

realloc'ing slap_known_controls.

LDAP_OPT_X_TLS_CONNECT_CB and LDAP_OPT_X_TLS_CONNECT_ARG
with int (LDAP_TLS_CONNECT_CB) (LDAP *ld, SSL *ssl, SSL_CTX *ctx, void *arg)
To be called whenever the client library allocates a new SSL* handle.