#2893 Bogus error messages when a file starts with a ';'

[Alan Cox]

SDCC says "ISO C forbids an empty source file" and also complains about a syntax error if the file starts with a semi-colon.

The synax error is correct for ISO C, the empty source file is clearly wrong.

[Philipp Klaus Krause]

In SDCC.y, we have a rule

file
   : /* empty */
     {
       werror(W_EMPTY_SOURCE_FILE);
     }
   | translation_unit
   ;

So if there is further input, which can't be lexed, we get the empty source file error even for nonempty files.

In [r13845], I improved the situation a bit (sdcc now behaves like gcc), the error message now mentions an "empty translation unit", which at least fixes the related case of a source file containing only preprocessing directives.