gallium: Return 'Mesa Contributors' for GL_VENDOR for community drivers that...

gallium: Return 'Mesa Contributors' for GL_VENDOR for community drivers that hooked with ".get_vendor ="

Signed-off-by: Yonggang Luo <luoyonggang@gmail.com>
225 jobs for !19247 with update-vendor in 7 seconds (queued for 9 seconds)
latest merge request