cmake: Define HAVE_FREEGLUT when glutInitContextProfile symbol is present.

Just like the configure.ac does.

Trivial.
glxinfo/wglinfo: reverse order of the gl_versions[] array

By going from newest to oldest we can simplify the glxinfo/wglinfo
loops over the possible GL versions.

Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
geom-stipple-lines: use VBO, specify number of verts on cmd line

If no command line argument is given, draw 50 points (25 lines).
geom-wide-lines: use VBO, specify number of verts on cmd line
cmake: Don't use gcc specific warnings with g++.

Avoids "warning: command line option ‘-W...’ is valid for Ada/C/ObjC but not for
C++".

Reviewed-by: Roland Scheidegger <sroland@vmware.com>
tests,trival,fp,vp: Rename errno with errnum.

Prevents warnings on MinGW due to conflicting linkage types for errno.

Reviewed-by: Roland Scheidegger <sroland@vmware.com>
wgl: Ensure PIXELFORMATDESCRIPTOR members are zeroed.

I suddenly started seeing many simple GL apps, including wglinfo,
choosing Microsoft GDI OpenGL implementation, even though hardware
accelerated pixel formats were available.

It turned out that:
- the screen was in 16bpp mode (some WHCK tests have the nasty habit
  of doing that)
- NVIDIA opengl driver only reports R5G6B5 pixel formats (ie no alpha
  bits) in this case
- non-zero cAlphaBits was being passed to ChoosePixelformat (or in the
  wglinfo case, garbage, as the structure wasn't being properly zeroed)
- ChoosePixelFormat will choose a SW pixel format if has to in order to
  honour non-zero cAlphaBits.

At least on the wglinfo and friends case the alpha bits are not needed,
so this change will make sure that HW accelerated formats will be chosen
before SW ones.

Reviewed-by: Roland Scheidegger <sroland@vmware.com>