mesa: Change "BRIAN PAUL" to "THE AUTHORS" in license text.

Generated automatically be the following shell command:
$ git grep 'BRIAN PAUL BE LIABLE' | sed 's/:.*$//g' | xargs -I '{}' \
  sed -i 's/BRIAN PAUL/THE AUTHORS/' {}

The intention here is to protect all authors, not just Brian Paul.  I
believe that was already the sensible interpretation, but spelling it
out is probably better.

More practically, it also prevents people from accidentally copy &
pasting the license into a new file which says Brian is not liable when
he isn't even one of the authors.

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

include/GL/glx_mangle.h

@@ -17,7 +17,7 @@
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
- * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
  * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  */