softpipe: implement separate depth-stencil clear

The CAP is going away.

Reviewed-by: Brian Paul <brianp@vmware.com>
st/mesa: always assume separate depth and stencil clear is supported

All drivers implement it now.

Reviewed-by: Brian Paul <brianp@vmware.com>
gallium: remove PIPE_CAP_DEPTHSTENCIL_CLEAR_SEPARATE

Reviewed-by: Brian Paul <brianp@vmware.com>
st/mesa: fix glClear with different colormask for each colorbuffer

Reviewed-by: Brian Paul <brianp@vmware.com>
st/mesa: simplify conditionals in Clear

just check depth and stencil separately, the outcome is the same

Reviewed-by: Brian Paul <brianp@vmware.com>
st/mesa: remove dead conditional in Clear

I think the conditional always evaluates to false.

If I understand the code in core Mesa correctly, depthBits or stencilBits
is 0 if the depth or stencil renderbuffer is NULL, respectively.

Reviewed-by: Brian Paul <brianp@vmware.com>
st/mesa: fix InternalFormat for Z24X8 window-system buffers

This probably doesn't fix anything, but it's good to be consistent.

Reviewed-by: Brian Paul <brianp@vmware.com>
gallium/util: fix glClear with MRT by making the FS write to all cbufs

Reviewed-by: Brian Paul <brianp@vmware.com>
st/mesa: use a generic varying to pass the clear color to the FS

The color varying may have reduced precision or be even clamped.

Reviewed-by: Brian Paul <brianp@vmware.com>
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.
Suppress clang's warnings about unused CFLAGS and CXXFLAGS.
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.