lib: c: pthread: implement per-thread errno storage

lib/libc/pthread/thread/errno.c

@@ -0,0 +1,12 @@
+#include "pthread.h"
+
+#include <mango/log.h>
+#include <pthread.h>
+#include <stdio.h>
+
+int *__errno_location(void)
+{
+	struct __pthread *self = pthread_self();
+	kern_logf("using pthread errno %p", &self->thr_errno);
+	return &self->thr_errno;
+}

lib/libc/pthread/thread/pthread.h

@@ -9,6 +9,7 @@ enum pthread_flags {
 
 struct __pthread {
 	struct __pthread *thr_self;
+	int thr_errno;
 	enum pthread_flags thr_flags;
 	kern_handle_t thr_handle;
 	void *thr_map_base;