Remove use of _CALL_ELF which is not correct inside compiler

  This solve cross-endian compilation for powerpc64-linux target

compiler/ppcgen/cgppc.pas

@@ -740,7 +740,7 @@ unit cgppc;
      case target_info.abi of
        abi_powerpc_aix:
          result:=LA_RTOC_AIX;
-{$if defined(powerpc64) and defined(_CALL_ELF) and (_CALL_ELF = 1)}
+{$if defined(powerpc64)}
        { no TOC on Linux/ppc32 }
        abi_powerpc_elfv1:
          result:=LA_RTOC_SYSV;