- add libbb function str_tolower to convert a string to lowercase.

- shrink wget a bit

libbb/str_tolower.c

@@ -0,0 +1,13 @@
+/* vi set: sw=4 ts=4: */
+/* Convert string str to lowercase, return str.
+ *
+ * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
+ */
+#include "libbb.h"
+char* str_tolower(char *str)
+{
+	char *c;
+	for (c = str; *c; ++c)
+		*c = tolower(*c);
+	return str;
+}