i965: Add .gitignore file to exclude automake build artifacts from git.

i965: Add .gitignore file to exclude automake build artifacts from git.

With the conversion to automake in commit
e326480e4ebe8687948041c2dc5f5b7595559a2e, several additional build
artifacts are created:

  src/mesa/drivers/dri/i965/.deps/
  src/mesa/drivers/dri/i965/.libs/
  src/mesa/drivers/dri/i965/Makefile
  src/mesa/drivers/dri/i965/Makefile.in
  src/mesa/drivers/dri/i965/i965_dri.la
  src/mesa/drivers/dri/i965/i965_symbols_test

This patch adds all of these files to .gitignore.

Reviewed-by: Matt Turner <mattst88@gmail.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>