in code and not in constants. In the case of primitive types constant nodes
are used while complex types like arrays, records and objects use a local
variable which is initialized to zero once at the entry of the method (the
variable is reused if Default() is used for the same type multiple times in
the same method). For this a new compilerproc was added which uses FillChar
to initialize the given memory area to zero.
This fixes Mantis #9420.

+ psystem.pas: Added Default symbol to system unit
+ htypechk.pas: Added function "is_valid_for_default" which checks recursively
                whether the given type can be used with Default at all. 
                Forbidden types are files, helpers, ObjC and C++ types. This
                check is used for records, arrays and objects only if the mode
                is a non-Delphi one, as Delphi ignores these types on lower
                levels.
+ msg/errore.msg: Added error message for unsupported types for Default()
+ symconst.pas: Added a new enum value vo_is_default_var which is used for the
                local variables utilized by Default() so their initalization
                and finalization can be avoided.
+ pexpr.pas: Add handling of Default() intrinsic to "statement_syssym"
+ ninl.pas: Extended tinlinenode by a method which returns the correct node for
            a Default() and used that method in handle_typecheck.
* ncgutil.pas: Check for new flag "vo_is_default_var" when initializing and
               finalizing local variables.
* ppu.pas: increase PPU version
+ psub.pas: 
  * Added a new routine which zeros defaultvars of a symtable.
  * Use this routine inside "initializevars".
  * Also use this routine to initialize the staticsymtable of the unit/program.
* Adjusted ppudump, because of the new enum value.
+ Added implementation of fpc_zeromem to system unit.
+ Added tests for Default()

git-svn-id: trunk@20629 -