Converting more configs to use generic infra, and moving defaults to config.c

Changes in behavior:
- Change server.stream_node_max_entries from int64_t to long long, so that it can be used by the generic infra
- standard error reply instead of "repl-backlog-size must be 1 or greater" and such
- tls-port and a few TLS booleans were readable (config get) even when USE_OPENSSL was off (now they aren't)
- syslog-enabled, syslog-ident, cluster-enabled, appendfilename, and supervised didn't have a get (now they do)
- pidfile was initialized to NULL in InitServerConfig but had CONFIG_DEFAULT_PID_FILE in rewriteConfig (so the real default was "", but rewrite would cause it to be set), fixed the rewrite.
- TLS config in server.h was uninitialized (if no tls config args were provided)

Adding test for sanity and coverage

src/cluster.h

@@ -13,15 +13,10 @@
 
 /* The following defines are amount of time, sometimes expressed as
  * multiplicators of the node timeout value (when ending with MULT). */
-#define CLUSTER_DEFAULT_NODE_TIMEOUT 15000
-#define CLUSTER_DEFAULT_SLAVE_VALIDITY 10 /* Slave max data age factor. */
-#define CLUSTER_DEFAULT_REQUIRE_FULL_COVERAGE 1
-#define CLUSTER_DEFAULT_SLAVE_NO_FAILOVER 0 /* Failover by default. */
 #define CLUSTER_FAIL_REPORT_VALIDITY_MULT 2 /* Fail report validity. */
 #define CLUSTER_FAIL_UNDO_TIME_MULT 2 /* Undo fail if master is back. */
 #define CLUSTER_FAIL_UNDO_TIME_ADD 10 /* Some additional time. */
 #define CLUSTER_FAILOVER_DELAY 5 /* Seconds */
-#define CLUSTER_DEFAULT_MIGRATION_BARRIER 1
 #define CLUSTER_MF_TIMEOUT 5000 /* Milliseconds to do a manual failover. */
 #define CLUSTER_MF_PAUSE_MULT 2 /* Master pause manual failover mult. */
 #define CLUSTER_SLAVE_MIGRATION_DELAY 5000 /* Delay for slave migration. */