re-add logic for ignoring failure of ld.so symlink installation

this was inadvertently removed when switching to the new install.sh.

Makefile

@@ -157,7 +157,7 @@ $(DESTDIR)$(includedir)/%: include/%
 	$(INSTALL) -D -m 644 $< $@
 
 $(DESTDIR)$(LDSO_PATHNAME): $(DESTDIR)$(libdir)/libc.so
-	$(INSTALL) -D -l $< $@
+	$(INSTALL) -D -l $< $@ || true
 
 install-libs: $(ALL_LIBS:lib/%=$(DESTDIR)$(libdir)/%) $(if $(SHARED_LIBS),$(DESTDIR)$(LDSO_PATHNAME),)