mesa: enable additional drivers for gallium-llvm x86/x86-64

mesa: enable additional drivers for gallium-llvm x86/x86-64

The additional Gallium drivers are needed for open source ATI Radeon
and NVIDIA graphics drivers.

The radeonsi and r600 drivers require LLVM 3.3 built with r600
PACKAGECONFIG so they must be explicitly enabled by adding r600 to the
mesa PACKAGECONFIG.

(From OE-Core rev: 1d08cef09cc7cbf682e8b372987fe4456961272b)

Signed-off-by: Jonathan Liu <net147@gmail.com>
Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>