If we're not building with glibc, then add its basename definition manually

diff --git a/tools/attr.c b/tools/attr.c
index f12e4af..d321b37 100644
--- a/tools/attr.c
+++ b/tools/attr.c
@@ -33,6 +33,15 @@
 
 #include "misc.h"
 
+#if !defined(__GLIBC__)
+char *
+basename (const char *filename)
+{
+  char *p = strrchr (filename, '/');
+  return p ? p + 1 : (char *) filename;
+}
+#endif
+
 #define	SETOP		1		/* do a SET operation */
 #define	GETOP		2		/* do a GET operation */
 #define	REMOVEOP	3		/* do a REMOVE operation */