Bump default value of WARNS for modules from 3 to 5, and
explicitly set WARNS for modules that fail with WARNS=5.

Also, turn on -Wno-missing-noreturn for clang for some files.

At the moment, among ~ 360 modules,
- 2 (lua and zfs) need WARNS=0
- 1 (solaris) needs WARNS=1
- 136 need WARNS=3 (mostly due to sign-compare)
- 4 need WARNS=4
- others can be compiled with WARNS=5

Discussed on tech-kern.

branches: 1.1.2; 1.1.4; 1.1.12; 1.1.16; 1.1.20;
Add new example kernel module in Lua luareadhappy

This example presents a C module with its device (/dev entry) and its
content generator with algorithm defined in Lua state. The Lua state can
be changed dynamically from userland, without interruption of read(2) over
the device.

This is an example how to call Lua code from C.

branches: 1.1.2; 1.1.4; 1.1.12; 1.1.16;
Add new example kernel module in Lua luareadhappy

This example presents a C module with its device (/dev entry) and its
content generator with algorithm defined in Lua state. The Lua state can
be changed dynamically from userland, without interruption of read(2) over
the device.

This is an example how to call Lua code from C.

Align major numbers in example modules with sys/conf/majors

Patch submitted by: Aditya Vardhan Padala (silv3r)

branches: 1.1.2; 1.1.4; 1.1.12; 1.1.16; 1.1.20; 1.1.26;
Add new example kernel module in Lua luareadhappy

This example presents a C module with its device (/dev entry) and its
content generator with algorithm defined in Lua state. The Lua state can
be changed dynamically from userland, without interruption of read(2) over
the device.

This is an example how to call Lua code from C.