Fix for Mantis #25215.

compiler/scanner.pas, tscannerfile.readtoken:
  * after trying to read a _INTCONST check whether a valid first character for an identifier follows and give a syntax error if that is not the case

+ added test


git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@25835 3ad0048d-3df7-0310-abae-a5850022a9f2