Choose another way to fix the issue from r5804: When parsing the directory

name, add a file mask, so the result is "$0:*" or similar. When specified like
this, the drive accepts the r/o specifier ",R" so we don't have to complicate
the code in open().


git-svn-id: svn://svn.cc65.org/cc65/trunk@5805 b7a2c559-68d2-44c3-8de9-860c34a00d81

libsrc/cbm/filename.s

@@ -125,6 +125,15 @@ drivedone:
         stx     fnbuf+1
         sta     fnbuf+0
 
+; Add the file mask
+
+        lda     #':'
+        sta     fnbuf+2
+        lda     #'*'
+        sta     fnbuf+3
+        lda     #4
+        sta     fnlen
+
 ; No need to check the name. Length is already 2
 
         lda     #0              ; ok flag