add prlimit64(2) syscall to COMPAT_LINUX and COMPAT_LINUX32

sys/compat: Memset zero before copyout.

Just in case of uninitialized padding which would lead to kernel
stack disclosure. If the compiler can prove the memset redundant
then it can optimize it away; otherwise better safe than sorry.

LINUX_RLIM_INFINITY doesn't fit into the value range for linux32, so
introduce a variant with correct value.

branches: 1.10.16; 1.10.26;
Make the emulations, exec formats, coredump, NFS, and the NFS server
into modules. By and large this commit:

- shuffles header files and ifdefs
- splits code out where necessary to be modular
- adds module glue for each of the components
- adds/replaces hooks for things that can be installed at runtime

branches: 1.9.2;
Kill a few linux32 syscalls identical to netbsd32 ones.
No functional changes expected.

branches: 1.8.6; 1.8.10; 1.8.12; 1.8.16;
Convert all the system call entry points from:
int foo(struct lwp *l, void *v, register_t *retval)
to:
int foo(struct lwp *l, const struct foo_args *uap, register_t *retval)
Fixup compat code to not write into 'uap' and (in some cases) to actually
pass a correctly formatted 'uap' structure with the right name to the
next routine.
A few 'compat' routines that just call standard ones have been deleted.
All the 'compat' code compiles (along with the kernels required to test
build it).
98% done by automated scripts.

branches: 1.7.4;
ANSIfy most of the function definitions in sys/compat (but not ndis).
All by the magic of sed ...

branches: 1.6.6; 1.6.8; 1.6.16;
There is no need to use the stackgap for get/setrlimit.

Change all the NETBSD32PTR64(SCARG(uap, xxx))) to SCARG_P32(uap, xxx).

branches: 1.4.2; 1.4.4; 1.4.6;
Kill caddr_t; there will be some MI fallout, but it will be fixed shortly.

branches: 1.3.2;
Merge newlock2 to head.

branches: 1.2.4; 1.2.6;
- Complete exit_group() implementation. We now maintain a list of Linux
threads in a processes and kill them properly. The code is a bit too
complicated, but I could not find a simplier way of dealing with it

- Change getpid() and getppid() semantics to match what Linux does,
and implement gettid(). In the Linux kernel, threads are implemnted
as plain old processes. A thread group is just a set of processes,
with the parent called leader. Thread ID, which are returned by gettid(),
are just the PID of the plain old processes, and getpid() returns the
PID of the thread group leader.

- Remove struct linux32_emuldata. COMPAT_LINUX32 uses a lot of COMPAT_LINUX
code, where a struct linux_emuldata is assumed. By having distinct emuldata
structure with different sizes and layouts, we caused kernel memory
corruptions.

- Fix setprioriry() and getpriority()

Thanks to Nicolas Joly for tracking down the problem and providing me the
hardware to fix them.

branches: 1.1.2; 1.1.4; 1.1.10; 1.1.14; 1.1.16;
Add initial (but unfinished) COMPAT_LINUX32 for amd64. This is good enough so
that the i386 license manager part of amd64 version of Fluent works.

While I'm here, add SysV IPC to COMPAT_LINUX/amd64

sys/compat: Memset zero before copyout.

Just in case of uninitialized padding which would lead to kernel
stack disclosure. If the compiler can prove the memset redundant
then it can optimize it away; otherwise better safe than sorry.

LINUX_RLIM_INFINITY doesn't fit into the value range for linux32, so
introduce a variant with correct value.

branches: 1.10.16; 1.10.26;
Make the emulations, exec formats, coredump, NFS, and the NFS server
into modules. By and large this commit:

- shuffles header files and ifdefs
- splits code out where necessary to be modular
- adds module glue for each of the components
- adds/replaces hooks for things that can be installed at runtime

branches: 1.9.2;
Kill a few linux32 syscalls identical to netbsd32 ones.
No functional changes expected.

branches: 1.8.6; 1.8.10; 1.8.12; 1.8.16;
Convert all the system call entry points from:
int foo(struct lwp *l, void *v, register_t *retval)
to:
int foo(struct lwp *l, const struct foo_args *uap, register_t *retval)
Fixup compat code to not write into 'uap' and (in some cases) to actually
pass a correctly formatted 'uap' structure with the right name to the
next routine.
A few 'compat' routines that just call standard ones have been deleted.
All the 'compat' code compiles (along with the kernels required to test
build it).
98% done by automated scripts.

branches: 1.7.4;
ANSIfy most of the function definitions in sys/compat (but not ndis).
All by the magic of sed ...

branches: 1.6.6; 1.6.8; 1.6.16;
There is no need to use the stackgap for get/setrlimit.

Change all the NETBSD32PTR64(SCARG(uap, xxx))) to SCARG_P32(uap, xxx).

branches: 1.4.2; 1.4.4; 1.4.6;
Kill caddr_t; there will be some MI fallout, but it will be fixed shortly.

branches: 1.3.2;
Merge newlock2 to head.

branches: 1.2.4; 1.2.6;
- Complete exit_group() implementation. We now maintain a list of Linux
threads in a processes and kill them properly. The code is a bit too
complicated, but I could not find a simplier way of dealing with it

- Change getpid() and getppid() semantics to match what Linux does,
and implement gettid(). In the Linux kernel, threads are implemnted
as plain old processes. A thread group is just a set of processes,
with the parent called leader. Thread ID, which are returned by gettid(),
are just the PID of the plain old processes, and getpid() returns the
PID of the thread group leader.

- Remove struct linux32_emuldata. COMPAT_LINUX32 uses a lot of COMPAT_LINUX
code, where a struct linux_emuldata is assumed. By having distinct emuldata
structure with different sizes and layouts, we caused kernel memory
corruptions.

- Fix setprioriry() and getpriority()

Thanks to Nicolas Joly for tracking down the problem and providing me the
hardware to fix them.

branches: 1.1.2; 1.1.4; 1.1.10; 1.1.14; 1.1.16;
Add initial (but unfinished) COMPAT_LINUX32 for amd64. This is good enough so
that the i386 license manager part of amd64 version of Fluent works.

While I'm here, add SysV IPC to COMPAT_LINUX/amd64