Minor on hb_blob_create_from_file, reuse ferror result

Oops

src/hb-blob.cc

diff --git a/src/hb-blob.cc b/src/hb-blob.cc
index d17627f..d29c6b2 100644
--- a/src/hb-blob.cc
+++ b/src/hb-blob.cc
@@ -618,7 +618,7 @@
 
     int err = ferror (fp);
     if (unlikely (err == EINTR)) continue;
-    if (unlikely (ferror (fp))) goto fread_fail;
+    if (unlikely (err)) goto fread_fail;
 
     len += addition;
   }