* disallow pushfd/popfd for x86_64 (mantis #14862)
  * fixed assembling popfq with the internal assembler (it needs a rex.w
    prefisx, while pushfq doesn't)
  * changed the default opcode size of pushf/popf/pusha/popa in
    {$asmmode intel} from "native size" to 16 bit (compatible with Intel
    manuals and Kylix; in AT&T mode, the default size for those operations
    remains the native one)
  * changed pushf/popf in rtl/i386/* into pushfd/popfd because of the
    previous change

git-svn-id: trunk@15546 -