* fixed r27320 for darwin, as its mangled names get prefixed with '_'
    and hence the generated mangled name did not start with a '$' as
    expected

git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@27357 3ad0048d-3df7-0310-abae-a5850022a9f2
  * fixed compilation for i8086 with 2.6.x (it gave an unreachable code
    warning)

git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@27358 3ad0048d-3df7-0310-abae-a5850022a9f2
  - removed {$ifdef compress} code (it hasn't been activated/maintained since
    a very long time)

git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@27359 3ad0048d-3df7-0310-abae-a5850022a9f2
  * removed {$ifndef i8086} in tx86vecnode, instead reset cvecnode to
    tcgvecnode in the n8086mem initcode

git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@27360 3ad0048d-3df7-0310-abae-a5850022a9f2
  + support overriding tdef/tsym methods with target-specific functionality:
   o made all (non-abstract) tdef and tsym constructors virtual
   o added c*def/c*sym classref types for every (non-abstract) t*def/t*sym
     class
   o added cpusym unit for every architecture that derives a tcpu*def/tcpu*sym
     class from the base classes, and initialises the c*def/c*sym classes with
     them. This is done so that the llvm target will be able to derive from
     the tcpu*def/sym classes without umpteen ifdefs, and it also means that
     the WPO can devirtualise everything because the c* variables are only
     initialised with one class type
   o replaced all t*def/t*sym constructor calls with c*def/c*sym constructor
     calls

git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@27361 3ad0048d-3df7-0310-abae-a5850022a9f2