added backtracing code using libunwind

moo/configure

@@ -657,6 +657,8 @@ ENABLE_MOD_FFI_FALSE
 ENABLE_MOD_FFI_TRUE
 ENABLE_MOD_CON_FALSE
 ENABLE_MOD_CON_TRUE
+ENABLE_LIBUNWIND_FALSE
+ENABLE_LIBUNWIND_TRUE
 ENABLE_LIBLTDL_FALSE
 ENABLE_LIBLTDL_TRUE
 ENABLE_STATIC_MODULE_FALSE
@@ -787,7 +789,6 @@ infodir
 docdir
 oldincludedir
 includedir
-runstatedir
 localstatedir
 sharedstatedir
 sysconfdir
@@ -826,6 +827,7 @@ enable_cxx
 enable_dynamic_module
 enable_static_module
 enable_libltdl
+enable_libunwind
 enable_mod_con
 enable_mod_ffi
 enable_mod_sck
@@ -883,7 +885,6 @@ datadir='${datarootdir}'
 sysconfdir='${prefix}/etc'
 sharedstatedir='${prefix}/com'
 localstatedir='${prefix}/var'
-runstatedir='${localstatedir}/run'
 includedir='${prefix}/include'
 oldincludedir='/usr/include'
 docdir='${datarootdir}/doc/${PACKAGE_TARNAME}'
@@ -1136,15 +1137,6 @@ do
   | -silent | --silent | --silen | --sile | --sil)
     silent=yes ;;
 
-  -runstatedir | --runstatedir | --runstatedi | --runstated \
-  | --runstate | --runstat | --runsta | --runst | --runs \
-  | --run | --ru | --r)
-    ac_prev=runstatedir ;;
-  -runstatedir=* | --runstatedir=* | --runstatedi=* | --runstated=* \
-  | --runstate=* | --runstat=* | --runsta=* | --runst=* | --runs=* \
-  | --run=* | --ru=* | --r=*)
-    runstatedir=$ac_optarg ;;
-
   -sbindir | --sbindir | --sbindi | --sbind | --sbin | --sbi | --sb)
     ac_prev=sbindir ;;
   -sbindir=* | --sbindir=* | --sbindi=* | --sbind=* | --sbin=* \
@@ -1282,7 +1274,7 @@ fi
 for ac_var in	exec_prefix prefix bindir sbindir libexecdir datarootdir \
 		datadir sysconfdir sharedstatedir localstatedir includedir \
 		oldincludedir docdir infodir htmldir dvidir pdfdir psdir \
-		libdir localedir mandir runstatedir
+		libdir localedir mandir
 do
   eval ac_val=\$$ac_var
   # Remove trailing slashes.
@@ -1435,7 +1427,6 @@ Fine tuning of the installation directories:
   --sysconfdir=DIR        read-only single-machine data [PREFIX/etc]
   --sharedstatedir=DIR    modifiable architecture-independent data [PREFIX/com]
   --localstatedir=DIR     modifiable single-machine data [PREFIX/var]
-  --runstatedir=DIR       modifiable per-process data [LOCALSTATEDIR/run]
   --libdir=DIR            object code libraries [EPREFIX/lib]
   --includedir=DIR        C header files [PREFIX/include]
   --oldincludedir=DIR     C header files for non-gcc [/usr/include]
@@ -1495,6 +1486,7 @@ Optional Features:
   --enable-static-module  build modules statically into the main
                           library(default. no)
   --enable-libltdl        use libltdl(default. no)
+  --enable-libunwind      use libunwind(default. no)
   --enable-mod-con        enable mod/con (default. yes)
   --enable-mod-ffi        enable mod/ffi (default. yes)
   --enable-mod-sck        enable mod/sck (default. yes)
@@ -21528,6 +21520,34 @@ else
 fi
 
 
+# Check whether --enable-libunwind was given.
+if test "${enable_libunwind+set}" = set; then :
+  enableval=$enable_libunwind; enable_libunwind_is=$enableval
+else
+  enable_libunwind_is=no
+
+fi
+
+if test "x${enable_libunwind_is}" = "xyes"
+then
+	if test "x${ac_cv_header_unwind_h}" = "xyes"  -a "${UNWIND_LIBS}" != ""
+	then
+
+$as_echo "#define MOO_ENABLE_LIBUNWIND /**/" >>confdefs.h
+
+	else
+		enable_libunwind_is="no"
+	fi
+fi
+ if test "x${enable_libunwind_is}" = "xyes"; then
+  ENABLE_LIBUNWIND_TRUE=
+  ENABLE_LIBUNWIND_FALSE='#'
+else
+  ENABLE_LIBUNWIND_TRUE='#'
+  ENABLE_LIBUNWIND_FALSE=
+fi
+
+
 # Check whether --enable-mod-con was given.
 if test "${enable_mod_con+set}" = set; then :
   enableval=$enable_mod_con; enable_mod_con_is=$enableval
@@ -21814,6 +21834,10 @@ if test -z "${ENABLE_LIBLTDL_TRUE}" && test -z "${ENABLE_LIBLTDL_FALSE}"; then
   as_fn_error $? "conditional \"ENABLE_LIBLTDL\" was never defined.
 Usually this means the macro was only invoked conditionally." "$LINENO" 5
 fi
+if test -z "${ENABLE_LIBUNWIND_TRUE}" && test -z "${ENABLE_LIBUNWIND_FALSE}"; then
+  as_fn_error $? "conditional \"ENABLE_LIBUNWIND\" was never defined.
+Usually this means the macro was only invoked conditionally." "$LINENO" 5
+fi
 if test -z "${ENABLE_MOD_CON_TRUE}" && test -z "${ENABLE_MOD_CON_FALSE}"; then
   as_fn_error $? "conditional \"ENABLE_MOD_CON\" was never defined.
 Usually this means the macro was only invoked conditionally." "$LINENO" 5