With --enable-bfd-backtraces, use binutils libbfd to resolve backtraces

The invocation of addr2line to resolve backtrace source locations
is slow and cumbersome. When using libbfd directly, we can eliminate
the overhead of the process invocation. Even better, we can cache
library symbol names, bringing wicked fast lookups. As a neat bonus,
we can resolve static function names.

configure.in

@@ -194,6 +194,7 @@ ARG_ENABL_SET([coupling],       [enable IKEv2 plugin to couple peer certificates
 ARG_ENABL_SET([radattr],        [enable plugin to inject and process custom RADIUS attributes as IKEv2 client.])
 ARG_ENABL_SET([vstr],           [enforce using the Vstr string library to replace glibc-like printf hooks.])
 ARG_ENABL_SET([monolithic],     [build monolithic version of libstrongswan that includes all enabled plugins. Similarly, the plugins of charon are assembled in libcharon.])
+ARG_ENABL_SET([bfd-backtraces], [use binutils libbfd to resolve backtraces for memory leaks and segfaults.])
 
 dnl =========================
 dnl  set up compiler and flags
@@ -785,6 +786,14 @@ if test x$integrity_test = xtrue; then
 	)
 fi
 
+if test x$bfd_backtraces = xtrue; then
+	AC_HAVE_LIBRARY([bfd],[LIBS="$LIBS"],[AC_MSG_ERROR([binutils libbfd not found!])])
+	AC_CHECK_HEADER([bfd.h],[AC_DEFINE([HAVE_BFD_H],,[have binutils bfd.h])],
+		[AC_MSG_ERROR([binutils bfd.h header not found!])])
+	BFDLIB="-lbfd"
+	AC_SUBST(BFDLIB)
+fi
+
 AM_CONDITIONAL(USE_DEV_HEADERS, [test "x$dev_headers" != xno])
 if test x$dev_headers = xyes; then
 	dev_headers="$includedir/strongswan"