Remove the ANGLE_COMPILE_OPTIMIZATION_LEVEL precompiler definition override to default to D3DCOMPILE_OPTIMIZATION_LEVEL3.

BUG=322795
R=geofflang@chromium.org

Change-Id: I7d8a2676c3510d26e9f0876aa30c6d8b4ae89f24
Reviewed-on: https://chromium-review.googlesource.com/183995Tested-by: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Commit-Queue: Nicolas Capens <nicolascapens@google.com>