on AMD64, and the general case where the emulated platform has different
size pointers than we use natively:
- declare certain structure members as l_uintptr_t and use the new PTRIN
  and PTROUT macros to convert to and from native pointers.
- declare some structures __packed on amd64 when the layout would differ
  from that used on i386.
- include <machine/../linux32/linux.h> instead of <machine/../linux/linux.h>
  if compiling with COMPAT_LINUX32. This will need to be revisited before
  32-bit and 64-bit Linux emulation support can coexist in the same kernel.
- other small scattered changes.

This should be a no-op on i386 and Alpha.

- add wrappers for mmap2(2) and ftruncate64(2) system calls;
- don't spam console with printf's when VFAT_READDIR_BOTH ioctl(2) is invoked;
- add support for SOUND_MIXER_READ_STEREODEVS ioctl(2);
- make msgctl(IPC_STAT) and IPC_SET actually working by converting from
  BSD msqid_ds to Linux and vice versa;
- properly return EINVAL if semget(2) is called with nsems being negative.

Reviewed by:	marcel
Approved by:	marcel
Tested with:	LSB runtime test

Note ALL MODULES MUST BE RECOMPILED
make the kernel aware that there are smaller units of scheduling than the
process. (but only allow one thread per process at this time).
This is functionally equivalent to teh previousl -current except
that there is a thread associated with each process.

Sorry john! (your next MFC will be a doosie!)

Reviewed by: peter@freebsd.org, dillon@freebsd.org

X-MFC after:    ha ha ha ha

o  Introduce private types for use in linux syscalls for two reasons:
   1. establish type independence for ease in porting and,
   2. provide a visual queue as to which syscalls have proper
      prototypes to further cleanup the i386/alpha split.
   Linuxulator types are prefixed by 'l_'. void and char have not
   been "virtualized".

o  Provide dummy functions for all syscalls and remove dummy functions
   or implementations of truely obsolete syscalls.

o  Sanitize the shm*, sem* and msg* syscalls.

o  Make a first attempt to implement the linux_sysctl syscall. At this
   time it only returns one MIB (KERN_VERSION), but most importantly,
   it tells us when we need to add additional sysctls :-)

o  Bump the kenel version up to 2.4.2 (this is not the same as the
   KERN_VERSION MIB, BTW).

o  Implement new syscalls, of which most are specific to i386. Our
   syscall table is now up to date with Linux 2.4.2. Some highlights:
   -  Implement the 32-bit uid_t and gid_t bases syscalls.
   -  Implement a couple of 64-bit file size/offset bases syscalls.

o  Fix or improve numerous syscalls and prototypes.

o  Reduce style(9) violations while I'm here. Especially indentation
   inconsistencies within the same file are addressed. Re-indenting
   did not obfuscate actual changes to the extend that it could not
   be combined.

NOTE: I spend some time testing these changes and found that if there
      were regressions, they were not caused by these changes AFAICT.
      It was observed that installing a RH 7.1 runtime environment
      did make matters worse. Hangs and/or reboots have been observed
      with and without these changes, so when it failed to make life
      better in cases it doesn't look like it made it worse.

pointed out by: obrien

its own syscall rather than going through a demux function like
linux_ipc() on i386

AlphaLinux compat bits.  This will be better cleaned up soon.

Agreed to what ever was necessary by:	marcel