ldso: install backward compatibility symlink by default

Simplify the switch from uClibc to uClibc-ng suggested
by Alexey Brodkin <Alexey.Brodkin@synopsys.com>.
Gcc always uses .0 ld.so link, so install it by default.

ldso/ldso/Makefile.in

@@ -74,6 +74,8 @@ $(ldso): $(ldso:.$(ABI_VERSION)=)
 $(ldso:.$(ABI_VERSION)=): | $(top_builddir)lib
 $(ldso:.$(ABI_VERSION)=): $($(UCLIBC_LDSO_NAME)_OUT)/$(UCLIBC_LDSO_NAME)_so.a
 	$(call link.so,$(ldso_FULL_NAME),$(ABI_VERSION))
+	# link for backward compatibility
+	(cd $(top_builddir)lib; ln -sf $(UCLIBC_LDSO_NAME).so.$(ABI_VERSION) $(UCLIBC_LDSO_NAME).so.0 )
 
 $($(UCLIBC_LDSO_NAME)_OUT)/$(UCLIBC_LDSO_NAME)_so.a: $(ldso-y)
 	$(Q)$(RM) $@