$NetBSD$
avoid undaignosed libtool breakage
--- src/libbacktrace/configure.orig	2017-02-09 01:37:48.000000000 +0000
+++ src/libbacktrace/configure
@@ -7783,7 +7783,7 @@ fi
 LIBTOOL_DEPS="$ltmain"
 
 # Always use our own libtool.
-LIBTOOL='$(SHELL) $(top_builddir)/libtool'
+LIBTOOL='libtool'
 
 
 
