replace all '#ifdef HAVE_BACKTRACE' with '#ifdef HAVE_BACKTRACE_SYMBOLS' (samba configure script checks for 'backtrace_symbols' but not for 'backtrace')

--- lib/util/fault.c
+++ lib/util/fault.c
@@ -35,7 +35,7 @@
 
 static const char *progname;
 
-#ifdef HAVE_BACKTRACE
+#ifdef HAVE_BACKTRACE_SYMBOLS
 #include <execinfo.h>
 #elif HAVE_LIBEXC_H
 #include <libexc.h>
@@ -46,7 +46,7 @@
  */
 _PUBLIC_ void call_backtrace(void)
 {
-#ifdef HAVE_BACKTRACE
+#ifdef HAVE_BACKTRACE_SYMBOLS
 #ifndef BACKTRACE_STACK_SIZE
 #define BACKTRACE_STACK_SIZE 64
 #endif
--- source4/smbd/process_thread.c
+++ source4/smbd/process_thread.c
@@ -24,7 +24,7 @@
 #include "includes.h"
 #include "version.h"
 #include <pthread.h>
-#ifdef HAVE_BACKTRACE
+#ifdef HAVE_BACKTRACE_SYMBOLS
 #include <execinfo.h>
 #endif
 #include "system/wait.h"
@@ -383,7 +383,7 @@
 static void thread_log_suspicious_usage(const char* from, const char* info)
 {
 	DEBUG(1,("log_suspicious_usage: from %s info='%s'\n", from, info));
-#ifdef HAVE_BACKTRACE
+#ifdef HAVE_BACKTRACE_SYMBOLS
 	{
 		void *addresses[10];
 		int num_addresses = backtrace(addresses, 8);
@@ -407,7 +407,7 @@
 static void thread_print_suspicious_usage(const char* from, const char* info)
 {
 	printf("log_suspicious_usage: from %s info='%s'\n", from, info);
-#ifdef HAVE_BACKTRACE
+#ifdef HAVE_BACKTRACE_SYMBOLS
 	{
 		void *addresses[10];
 		int num_addresses = backtrace(addresses, 8);
@@ -490,7 +490,7 @@
 		SAMBA_VERSION_STRING));
 	DEBUG(0,("Please read the file BUGS.txt in the distribution\n"));
 	DEBUG(0,("===============================================================\n"));
-#ifdef HAVE_BACKTRACE
+#ifdef HAVE_BACKTRACE_SYMBOLS
 	{
 		void *addresses[10];
 		int num_addresses = backtrace(addresses, 8);