scanf: Do not test for EOF at the beginning of scanf processing.

If the format string is empty or contains only %n conversions, then nothing should be read from the stream, so no error should be indicated even if it is at EOF. If a directive does read from the stream and encounter EOF, that will be handled when the directive is processed.

This could cause scanf to pause waiting for input from the console in cases where it should not.

stdio.asm

@@ -6151,11 +6151,6 @@ ps       stz   ~assignments             no assignments yet
          stz   ~scanCount               no characters scanned
          stz   ~scanError               no scan error so far
          stz   ~eofFound                eof was not the first char
-         jsl   ~getchar                 test for eof
-         cmp   #EOF
-         bne   ps0
-         sta   ~eofFound
-ps0      jsl   ~putback
 
 ps1      lda   ~scanError               quit if a scan error has occurred
          bne   rm1