Fix BETTER_BACKTRACES library detection for Fedora/RedHat/CentOS

(closes ASTERISK-17842)
Reported by: Bryon Clark
Patches:
	20110512__issue19278.diff.txt uploaded by Tilghman Lesher (license 5003)
	configure_bfd_with_dl_and_iberty.patch uploaded by Bryon Clark (license 6157)


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.8@360488 65c4cc65-6c06-0410-ace0-fbb531ad65f3

configure.ac

@@ -1107,6 +1107,11 @@ AST_EXT_LIB_CHECK([ALSA], [asound], [snd_spcm_init], [alsa/asoundlib.h], [-lm -l
 
 AST_EXT_LIB_CHECK([BFD], [bfd], [bfd_openr], [bfd.h])
 
+if test "${PBX_BFD}" = "0"; then
+  # Fedora/RedHat/CentOS require extra libraries
+  AST_EXT_LIB_CHECK([BFD], [bfd], [bfd_check_format], [bfd.h], [-ldl -liberty])
+fi
+
 if test "x${OSARCH}" = "xlinux-gnu" ; then
   AST_EXT_LIB_CHECK([CAP], [cap], [cap_from_text], [sys/capability.h])
 fi