intel: Set screen's api mask according to hw capabilities (v3)

Before this patch, intelInitScreen2 set DRIScreen::api_mask with the hacky
heuristic below:

    if (gen >= 3)
        api_mask = GL | GLES1 | GLES2;
    else
        api_mask = 0;

This hack was likely broken on gen2 (i830), but I don't care enough to
properly investigate. It appears that every EGLConfig on i830 has
EGL_RENDERABLE_TYPE=0, and thus eglCreateContext will never succeed.
Anyway, moving on to living drivers...

With the arrival of EGL_OPENGL_ES3_BIT_KHR, this heuristic is now
insufficient. We must enable the GLES3 bit if and only if the driver is
capable of creating a GLES3 context. This requires us to determine the
maximum supported context version supported by the hardware/driver for
each api *during initialization of intel_screen*.

Therefore, this patch adds four new fields to intel_screen which indicate
the maximum supported context version for each api:
  max_gl_core_version
  max_gl_compat_version
  max_gl_es1_version
  max_gl_es2_version

The api mask is now correctly set as:

    api_mask = GL;
    if (max_gl_es1_version > 0)
        api_mask |= GLES1;
    if (max_gl_es2_version > 0)
        api_mask |= GLES2;

Tested against gen6 with piglit egl-create-context-verify-gl-flavor.
Verified that this patch does not change the set of exposed EGL context
flavors.

v2:
  - Replace the if-tree on gen with a switch, for Ian.
  - Unconditionally enable the DRI_API_OPENGL bit, for Ian.

v3:
  - Drop max gl version to 1.4 on gen3 if !has_occlusion_query,
    because occlusion queries entered core in 1.5. For Ian.

v4:
  - Drop ES2 version back to 2.0 due to rebase (Ian).

Signed-off-by: Chad Versace <chad.versace@linux.intel.com>
Reviewed-by: Ian Romanick <ian.d.romanick.intel.com>
intel: Move validation of context version into intelInitContext

Each driver (i830, i915, i965) used independent but similar code to
validate the requested context version. With the rececnt arrival of GLES3,
that logic has needed an update. Rather than apply identical updates to
each drivers validation code, let's just move the validation into the
shared routine intelInitContext.

This refactor required some incidental changes to functions
i830CreateContext and intelInitContext. For each function, this patch:
    - Adds context version parameters to the signature.
    - Adds a DRI_CTX_ERROR out param to the signature.
    - Sets the DRI_CTX_ERROR at each early return.

Tested against gen6 with piglit egl-create-context-verify-gl-flavor.
Verified that this patch does not change the set of exposed EGL context
flavors.

Signed-off-by: Chad Versace <chad.versace@linux.intel.com>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
dri: Define enum __DRI_API_GLES3

This enum corresponds to EGL_OPENGL_ES3_BIT_KHR.
Neither the GLX nor EGL layer use the enum yet.

I don't like the GLES bits. I'd prefer that all GLES APIs be exposed
through a single API bit, as is done in GLX_EXT_create_context_es_profile.
But, we need this GLES3 enum in order to do the plumbing necessary to
correctly support EGL_OPENGL_ES3_BIT_KHR as required by the
EGL_KHR_create_context spec.

Signed-off-by: Chad Versace <chad.versace@linux.intel.com>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
intel: Expose support for DRI_API_GLES3

If the hardware/driver combo supports GLES3, then set the GLES3 bit in
intel_screen's bitmask of supported DRI API's.  Neither the EGL nor GLX
layer uses the bit yet.

Signed-off-by: Chad Versace <chad.versace@linux.intel.com>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
egl/dri2: Add plumbing for EGL_OPENGL_ES3_BIT_KHR

Fixes error EGL_BAD_ATTRIBUTE in the tests below on Intel Sandybridge:
    * piglit egl-create-context-verify-gl-flavor, testcase OpenGL ES 3.0
    * gles3conform, revision 19700, when runnning GL3Tests with -fbo

This plumbing is added in order to comply with the EGL_KHR_create_context
spec. According to the EGL_KHR_create_context spec, it is illegal to call
eglCreateContext(EGL_CONTEXT_MAJOR_VERSION_KHR=3) with a config whose
EGL_RENDERABLE_TYPE does not contain the EGL_OPENGL_ES3_BIT_KHR. The
pertinent
portion of the spec is quoted below; the key word is "respectively".

  * If <config> is not a valid EGLConfig, or does not support the
    requested client API, then an EGL_BAD_CONFIG error is generated
    (this includes requesting creation of an OpenGL ES 1.x, 2.0, or
    3.0 context when the EGL_RENDERABLE_TYPE attribute of <config>
    does not contain EGL_OPENGL_ES_BIT, EGL_OPENGL_ES2_BIT, or
    EGL_OPENGL_ES3_BIT_KHR respectively).

To create this patch, I searched for all the ES2 bit plumbing by calling
`git grep "ES2_BIT\|DRI_API_GLES2" src/egl`, and then at each location
added a case for ES3.

Signed-off-by: Chad Versace <chad.versace@linux.intel.com>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Suppress clang's warnings about unused CFLAGS and CXXFLAGS.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
radeon, clover: Make it compile on LLVM >= r171366.
configure.ac: Save user {C,CXX}FLAGS and append them at end.

This way the user has the privilege of last decision and so the option to build an optimized debug build again.
gallium/auxiliary: Build libgallium shared.
Drop last parts of compatibility for the old Mesa build system.
mapi: Build libglapi always shared.
mesa: Build libmesa shared.
Install all internal shared libs to $(libdir)/mesa-$VERSION.
Makefile.am: s:-no-undefined:-Wl,--no-undefined to make it work.
gallium/drivers: Build libs -shared.
i915: Conditionally build an i915g driver instead of two i915 drivers.
configure: Build src/gtest at first.