intel-gpu-tools: Version information

intel-gpu-tools: Version information

Provide two arguments version, and verbose, which allow printing from an
arbitrary igt test. It will show system information (from build time,
not runtime), as well as the git SHA being used.

This will help reduce errors when people try to reproduce problems.

As an example if I want to verify someone is running the correct version
of a test, I could ask them to do:
bwidawsk@ironside ~/intel-gfx/intel-gpu-tools (master)$ sudo ./tests/gem_exec_nop --verbose
gem_exec_nop-git-3c5423b (Linux ironside 3.12.0-1-ARCH #1 SMP PREEMPT
Wed Nov 6 09:06:27 CET 2013 x86_64 GNU/Linux)
Time to exec x 1:		 35.000µs (ring=render)
Time to exec x 2:		 28.000µs (ring=render)
Time to exec x 4:		 20.000µs (ring=render)
Time to exec x 8:		 14.625µs (ring=render)
Time to exec x 16:		 11.188µs (ring=render)
Time to exec x 32:		 11.125µs (ring=render)
Time to exec x 64:		 10.328µs (ring=render)
Time to exec x 128:		 10.172µs (ring=render)
Time to exec x 256:		 10.234µs (ring=render)
Time to exec x 512:		 10.232µs (ring=render)
Time to exec x 1024:		 10.121µs (ring=render)
Time to exec x 2048:		 10.151µs (ring=render)
Time to exec x 4096:		 11.474µs (ring=render)
Time to exec x 8192:		  9.432µs (ring=render)
Time to exec x 16384:		  6.003µs (ring=render)
Time to exec x 32768:		  5.029µs (ring=render)
Time to exec x 65536:		  4.206µs (ring=render)
Time to exec x 131072:		  3.630µs (ring=render)
Subtest render: SUCCESS

--verbose is provided for completeness, but doesn't seem too useful at
the moement.

bwidawsk@ironside ~/intel-gfx/intel-gpu-tools (master)$ sudo ./tests/gem_exec_nop --version
gem_exec_nop-git-3c5423b (Linux ironside 3.12.0-1-ARCH #1 SMP PREEMPT
Wed Nov 6 09:06:27 CET 2013 x86_64 GNU/Linux)

I've put version.h in the root directory so that any subdir can access
it. I've added the tests usage since it's immediately useful, and done
easily via Daniels igt infrastructure work.

v2:
- Always print the version number.
- We want to print uname at runtime.
- Also prefix the i-g-t release version.

Signed-off-by: Ben Widawsky <ben@bwidawsk.net> (v1)
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>