ls: fix HAVE_STRVERSCMP check; add check for older uclibc versions

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/coreutils/ls.c b/coreutils/ls.c
index 6080f59..f11eb43 100644
--- a/coreutils/ls.c
+++ b/coreutils/ls.c
@@ -886,7 +886,7 @@
 	if (sort_opts == SORT_DIR) {
 		dif = S_ISDIR(d2->dn_mode) - S_ISDIR(d1->dn_mode);
 	} else
-#ifdef HAVE_STRVERSCMP && HAVE_STRVERSCMP == 1
+#if defined(HAVE_STRVERSCMP) && HAVE_STRVERSCMP == 1
 	if (sort_opts == SORT_VERSION) {
 		dif = strverscmp(d1->name, d2->name);
 	} else