[Bug other/58374] New: Wrong target check in configure.ac in libvtv

["hjl.tools at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58374

            Bug ID: 58374
           Summary: Wrong target check in configure.ac in libvtv
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: other
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hjl.tools at gmail dot com

configure.ac in libvtv in has

unset VTV_SUPPORTED
AC_MSG_CHECKING([for host support for vtable verification])
. ${srcdir}/configure.tgt
AC_MSG_RESULT($VTV_SUPPORTED)

# Decide if it's usable.
use_vtable_verify=no
if test "x$VTV_SUPPORTED" = "xyes"; then
  use_vtable_verify=yes
  AC_MSG_NOTICE(using vtable verification)
fi 

# Do not delete or change the following two lines.  For why, see
# http://gcc.gnu.org/ml/libstdc++/2003-07/msg00451.html
AC_CANONICAL_SYSTEM
target_alias=${target_alias-$host_alias}
AC_SUBST(target_alias)
GCC_LIBSTDCXX_RAW_CXX_FLAGS

It won't work for targets like i686-linux nor x86_64-linux since
configure.tgt only recognizes canonical targets.  The VTV_SUPPORTED
check should be moved after AC_CANONICAL_SYSTEM.