piglit-dispatch: Introduce OpenGL API spec files.

This is the first in a series of patches that replaces GLEW with a new
mechanism called "piglit-dispatch".

This patch introduces files which describe the OpenGL API in
machine-readable form.  These files are duplicates of those found at
http://www.opengl.org/registry/.

Later patches in the series will transform these spec files to C code.
piglit-dispatch: Corrections to OpenGL API spec files.

This patch corrects a few minor errors in the OpenGL API spec files
from http://www.opengl.org/registry/:

- ALL_ATTRIB_BITS was incorrectly defined as 0xFFFFFFFF.  The correct
  value is 0x000FFFFF, since ALL_ATTRIB_BITS is not meant to apply to
  MULTISAMPLE_BIT (see extension specs 3DFX_multisample,
  ARB_multisample, EXT_multisample, and SGIS_multisample).

- IsProgramARB and IsProgramNV were incorrectly marked as aliases of
  each other.  This is not the case, since IsProgram is used for GLSL
  programs, and IsProgramARB/IsProgramNV are used for assembly
  programs.

- GenVertexArraysAPPLE was incorrectly marked as an alias for
  "GenVertexArray".  There is no such function--the correct function
  is "GenVertexArrays".

- TransformFeedbackVaryingsNV was incorrectly marked as an alias for
  TransformFeedbackVaryings.  This is incorrect--the two functions
  interpret their arguments differently.  Similarly,
  GetTransformFeedbackVaryingNV was incorrectly marked as an alias for
  GetTransformFeedbackVarying.

- StencilFuncSeparateATI was incorrectly marked as an alias for
  StencilFuncSeparate.  This is incorrect--the two functions interpret
  their arguments differently.

- NV functions dealing with vertex attributes
  (GetVertexAttrib{d,f,i}vNV, VertexAttrib{1,2,3,4}{d,f,s}{,v}NV, and
  VertexAttrib4ub{,v}NV) were incorrectly marked as an alias for the
  corresponding core functions.  This is incorrect--NV extensions
  handle vertex attribute numbering differently.

The reason these errors were not caught by the maintainers of
opengl.org is likely because they don't affect the contents of the
glext.h header file.
piglit-dispatch: Additions to OpenGL API spec files.

This patch adds descriptions of the extensions
OES_compressed_paletted_texture, ATI_texture_compression_3dc, and
NVX_gpu_memory_info to the OpenGL API spec files.  The extension
OES_compressed_paletted_texture was previously commented out (since it
is part of GLES), and the others weren't present at all.
piglit-dispatch: Code generation script.

This patch contains the code generation script that converts the files
gl.spec, gl.tm, and enumext.spec into C code, as well as the CMake
directives to run the script.

Code generation occurs in two phases: first the script
glapi/parse_glspec.py converts the .spec and .tm files into an
intermediate JSON format, which is stored in glapi/glapi.json.  Then,
the script tests/util/gen_dispatch.py converts the JSON file into two
files, tests/util/generated_dispatch.c and
tests/util/generated_dispatch.h.

These files can be built by invoking "make piglit_dispatch_gen" from
the toplevel source directory.
piglit-dispatch: Add generated files.

This patch adds the files glapi/glapi.json,
tests/util/generated_dispatch.c, and tests/util/generated_dispatch.h,
which were generated using the command "make piglit_dispatch_gen".
piglit-dispatch: Remaining infrastructure.

Previous patches introduced code generation for the auto-generated
portions of the piglit-dispatch mechanism.  This patch supplies the
remaining hand-written code, which includes:

- Code to initialize piglit-dispatch.

- The actions to be taken when looking up a function, when function
  lookup fails, or when a function is unsupported.

- Code to determine whether piglit-dispatch has been initialized,
  which GL version is supported, and whether a given extension is
  supported.

- Code to look up a function using a name supplied at run-time.

- Definitions of basic GL types.
piglit-dispatch: Switch to using piglit-dispatch instead of GLEW.

Previous patches set up the piglit-dispatch infrastructure but did not
use it.  This patch enables piglit-dispatch and uses it instead of
GLEW.

No piglit regressions on Intel SandyBridge (Linux).
piglit-dispatch: Remove GLEW.

This patch removes the files glew.c and glew.h, which are no longer
used.  The "piglit-dispatch" mechanism is used instead.
Remove GLEW workarounds.

This patch removes workarounds that were in place to compensate for
bugs in GLEW.
glean: use piglit_get_proc_address().

Previously glean got the address of GL functions by directly calling
an OS-specific function (e.g. glXGetProcAddressARB(), dlsym(), or
wglGetProcAddress()).  This patch changes it to use
piglit_get_proc_address(), which uses piglit-dispatch.  This will help
pave the way for adapting glean to test using GLES and
forward-compatible contexts.