Revert "libubacktrace: fix config-symbol handling"

This reverts commit 7a080cd149c7b25d415d76506510d55b34819fc2.

This symbol is in fact different (as it is set no 'n').

libubacktrace/Makefile.in

@@ -45,7 +45,7 @@ lib-so-$(UCLIBC_HAS_BACKTRACE) += $(top_builddir)lib/libubacktrace.so
 
 objclean-y += CLEAN_libubacktrace
 
-ifeq ($(DOMULTI),)
+ifeq ($(DOMULTI),n)
 ifeq ($(DOPIC),y)
 $(top_builddir)lib/libubacktrace.so: $(top_builddir)lib/libubacktrace.a $(libdl.depend)
 else