Temporarily add fallback null path for backtrace

Makefile.am

@@ -51,9 +51,10 @@ UTIL_FILES   =	\
 
 if HAVE_EXECINFO
 UTIL_FILES += backtrace_execinfo.cpp
+else
+UTIL_FILES += backtrace_null.cpp
 endif
 
-
 CLEANFILES = json.cpp version.cpp ip.cpp
 EXTRA_DIST = json.cpp.rl version.cpp.rl ip.cpp.rl
 

backtrace_null.cpp

@@ -0,0 +1,17 @@
+#include "backtrace.hpp"
+
+#include <iostream>
+
+using namespace std;
+
+
+debug::backtrace::backtrace (void):
+    m_frames (DEFAULT_DEPTH) 
+{ ; }
+
+
+ostream&
+operator <<(ostream &os, const debug::backtrace &rhs) {
+    os << "null backtrace";
+    return os;
+}

configure.ac

@@ -85,12 +85,14 @@ AC_C_BIGENDIAN
 
 ##
 ## platform features
+COMMON_CFLAGS="$COMMON_CFLAGS -D_GNU_SOURCE"
+
 AC_FUNC_MMAP
 
-AC_CHECK_HEADER([execinfo.h], [break], [AC_MSG_ERROR([Missing backtrace support])])
-
+AC_CHECK_HEADER([execinfo.h], [break])
 AM_CONDITIONAL([HAVE_EXECINFO], [test x$ac_cv_header_execinfo_h = "xyes"])
 
+
 ##
 ## Debug features
 if test "x$cv_debugging" = "xyes"; then