made backtrace() calls optional to support uClibc

configure.in

@@ -96,6 +96,8 @@ dnl ==========================
 dnl  check required libraries
 dnl ==========================
 
+AC_CHECK_FUNCS(backtrace getifaddrs)
+
 AC_HAVE_LIBRARY([gmp],[LIBS="$LIBS"],[AC_MSG_ERROR([GNU Multi Precision library gmp not found])])	
 if test "$ldap" = "true"; then
     AC_HAVE_LIBRARY([ldap],[LIBS="$LIBS"],[AC_MSG_ERROR([LDAP enabled, but library ldap not found])])

src/charon/daemon.c

@@ -285,6 +285,7 @@ static void initialize(private_daemon_t *this, bool strict, bool syslog,
  */
 void signal_handler(int signal)
 {
+#ifndef HAVE_BACKTRACE
 	void *array[20];
 	size_t size;
 	char **strings;
@@ -294,13 +295,17 @@ void signal_handler(int signal)
 	strings = backtrace_symbols(array, size);
 
 	DBG1(DBG_DMN, "thread %u received %s. Dumping %d frames from stack:",
-		 signal == SIGSEGV ? "SIGSEGV" : "SIGILL", pthread_self(), size);
+		 pthread_self(), signal == SIGSEGV ? "SIGSEGV" : "SIGILL", size);
 
 	for (i = 0; i < size; i++)
 	{
 		DBG1(DBG_DMN, "    %s", strings[i]);
 	}
 	free (strings);
+#else /* !HAVE_BACKTRACE */
+	DBG1(DBG_DMN, "thread %u received %s",
+		 pthread_self(), signal == SIGSEGV ? "SIGSEGV" : "SIGILL");
+#endif /* HAVE_BACKTRACE */
 	DBG1(DBG_DMN, "killing ourself hard after SIGSEGV");
 	raise(SIGKILL);
 }

src/libstrongswan/utils/leak_detective.c

@@ -140,6 +140,7 @@ static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
  */
 static void log_stack_frames(void **stack_frames, int stack_frame_count)
 {
+#ifdef HAVE_BACKTRACE
 	char **strings;
 	size_t i;
 
@@ -152,6 +153,7 @@ static void log_stack_frames(void **stack_frames, int stack_frame_count)
 		DBG1("    %s", strings[i]);
 	}
 	free (strings);
+#endif /* HAVE_BACKTRACE */
 }
 
 /**