widen "Unicode in environment" check

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/libbb/unicode.c b/libbb/unicode.c
index 3519984..544528a 100644
--- a/libbb/unicode.c
+++ b/libbb/unicode.c
@@ -39,7 +39,7 @@
 	unicode_is_enabled = 1;
 
 	lang = getenv("LANG");
-	if (!lang || !strstr(lang, ".utf8"))
+	if (!lang || !(strstr(lang, ".utf") || strstr(lang, ".UTF")))
 		return;
 
 	unicode_is_enabled = 2;