libled: provide basename if GLIBC is not avialable

If GNU basename is not avilable, define it. It is safer to use that
rather than include libgen.h with XPG basename() definition.

Suggested in https://github.com/md-raid-utilities/ledmon/pull/
272#issuecomment-3596495739

Code copied from
md-raid-utilities/mdadm@9dbd11e

Signed-off-by: Bernd Kuhls <[email protected]>

Author: bkuhls

src/lib/libled_internal.h

@@ -70,4 +70,13 @@ led_status_t device_exclude_pattern_add(struct led_ctx *ctx, const char *path);
  */
 void lib_log(struct led_ctx *ctx, enum led_log_level_enum loglevel, const char *buf, ...)
 				__attribute__ ((format (printf, 3, 4)));
+
+/*
+ * Ensure GNU basename behavior on GLIBC less systems.
+ */
+#ifndef __GLIBC__
+#define basename(path) \
+	(strrchr((path), '/') ? strrchr((path), '/') + 1 : (path))
+#endif
+
 #endif