configure.ac: Do not enable -Wl,--no-undefined on Mac OS X.

This patch fixes this build error on Mac OS X.

  CCLD     libglapi.la
clang: warning: argument unused during compilation: '-pthread'
clang: warning: argument unused during compilation: '-pthread'
ld: unknown option: --no-undefined
clang: error: linker command failed with exit code 1 (use -v to see invocation)

Signed-off-by: Vinson Lee <vlee@freedesktop.org>
mesa: Add uninitialized_vars macro from the Linux kernel.
mesa/x86: Support SSE 4.1 detection on x86-64.

Uses the cpuid.h header provided by gcc and clang. Other platforms are
encouraged to switch.
mesa/x86: add SSE4.1 runtime detection.

Add a bit to _mesa_x86_features for SSE 4.1, along with macros to query.

Reviewed-by: Matt Turner <mattst88@gmail.com>
i965: Use SSE4.1 runtime detection for intel_miptree_map.

Previous it was a compile-time decision.

Reviewed-by: Matt Turner <mattst88@gmail.com>
mesa/x86: Brown bag fix for undeclared variable.
docs: Import 10.1.4 release notes, add news item.
scons: Fix x86_64 build.

x86/common_x86.c is required also for x86_64 builds.

Reviewed-by: Matt Turner <mattst88@gmail.com>
mesa: Rely on USE_X86_64_ASM.

This fixes MinGW x64 builds.  We don't use assembly on any of the
Windows builds, to avoid divergence between MSVC and MinGW when testing.

Reviewed-by: Matt Turner <mattst88@gmail.com>