Replace http://man7.org links with https://man7.org links.

I suspect the way http:// dies is that browsers just interpret it as
https:// anyway, but there's no reason not to just bulk fix all these at
source.

Change-Id: I38fa91728846d7c33207ef1bdadd4910eac9e941
diff --git a/libc/include/sys/stat.h b/libc/include/sys/stat.h
index f916573..0ea596b 100644
--- a/libc/include/sys/stat.h
+++ b/libc/include/sys/stat.h
@@ -205,7 +205,7 @@
 
 #if defined(__USE_GNU)
 /**
- * [statx(2)](http://man7.org/linux/man-pages/man2/statx.2.html) returns
+ * [statx(2)](https://man7.org/linux/man-pages/man2/statx.2.html) returns
  * extended file status information.
  *
  * Returns 0 on success and returns -1 and sets `errno` on failure.