patch 8.2.2039: viminfo is not written when creating a new file

Problem:    Viminfo is not written when creating a new file.
Solution:   Set "b_marks_read" in the new buffer. (Christian Brabandt,
            closes #7350)

src/bufwrite.c

@@ -2579,6 +2579,12 @@ nofail:
 #endif
     }
 
+#ifdef FEAT_VIMINFO
+    // Make sure marks will be written out to the viminfo file later, even when
+    // the file is new.
+    curbuf->b_marks_read = TRUE;
+#endif
+
     got_int |= prev_got_int;
 
     return retval;