Assignment of named empty string to ARRAY OF SHORTCHAR does not work. Refs: #128.
The compiler converts such a string assignment into s[0] := 0X.
The original object, i.e. the named string constant, was not cleared in this transformation
and was still used by the code generator with a value of obj.conval.intval = -1 (=DevCPM.ConstNotAlloc).

Signed-off-by: Josef Templ <josef.templ@gmail.com>