libubacktrace: Fix ASNEEDED emission

In master the variable is called SHARED_LIBNAME and not
SHARED_MAJORNAME.

Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>

Makefile.in

@@ -338,7 +338,7 @@ else
 endif
 ifeq ($(UCLIBC_HAS_BACKTRACE),y)
 # Add the AS_NEEDED entry for libubacktrace.so
-	if [ -f $(top_builddir)lib/libc.so -a -f $(PREFIX)$(RUNTIME_PREFIX)$(MULTILIB_DIR)/$(SHARED_MAJORNAME) ] ; then \
+	if [ -f $(top_builddir)lib/libc.so -a -f $(PREFIX)$(RUNTIME_PREFIX)$(MULTILIB_DIR)/$(SHARED_LIBNAME) ] ; then \
 		echo "GROUP ( $(UBACKTRACE_ASNEEDED) )" >> $(PREFIX)$(DEVEL_PREFIX)$(MULTILIB_DIR)/libc.so; \
 	fi
 endif