LDAP_THREAD_DEBUG revamping, cleanup, bug fixes.

Expand usage struct with magic numbers and state info.
Add options "noreinit", "nosync", "nomem", "threadID".  Remove "dupinit".
Detect address changes.  Turn off thread ID tracking by default.

include/ldap_int_thread.h

@@ -247,9 +247,25 @@ LDAP_BEGIN_DECL
 #define LDAP_UINTPTR_T	unsigned long
 #endif
 
-typedef union {
-	unsigned char			*ptr;
-	LDAP_UINTPTR_T			num;
+typedef enum {
+	ldap_debug_magic =	-(int) (((unsigned)-1)/19)
+} ldap_debug_magic_t;
+
+typedef enum {
+	/* Could fill in "locked" etc here later */
+	ldap_debug_state_inited = (int) (((unsigned)-1)/11),
+	ldap_debug_state_destroyed
+} ldap_debug_state_t;
+
+typedef struct {
+	/* Enclosed in magic numbers in the hope of catching overwrites */
+	ldap_debug_magic_t	magic;	/* bit pattern to recognize usages  */
+	LDAP_UINTPTR_T		self;	/* ~(LDAP_UINTPTR_T)&(this struct) */
+	union ldap_debug_mem_u {	/* Dummy memory reference */
+		unsigned char	*ptr;
+		LDAP_UINTPTR_T	num;
+	} mem;
+	ldap_debug_state_t	state;	/* doubles as another magic number */
 } ldap_debug_usage_info_t;
 
 typedef struct {