libbacktrace: don't fail tests if dwz fails

* Makefile.am (%_dwz): If dwz fails, use uncompressed debug info.
	* Makefile.in: Regenerate.

Makefile.am

@@ -304,9 +304,13 @@ if HAVE_DWZ
 	rm -f $@ $@_common.debug
 	cp $< $@_1
 	cp $< $@_2
-	$(DWZ) -m $@_common.debug $@_1 $@_2
-	rm -f $@_2
-	mv $@_1 $@
+	if $(DWZ) -m $@_common.debug $@_1 $@_2; then \
+	  rm -f $@_2; \
+	  mv $@_1 $@; \
+	else \
+	  echo "Ignoring dwz errors, assuming that test passes"; \
+	  cp $< $@; \
+	fi
 
 TESTS += btest_dwz