piglit: save all results

Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
compare: improve test case name for other dimensions

Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
compare: show user friendly commit tag

Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
git: add git tag cache

Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
add performance index for tlbflush and aim9

Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>