[mesa] Temporarily disable `-Wreorder-init-list` warnings

https://reviews.llvm.org/D59754 limits basic designated initialiizers
for c++2a. The patch includes new warnings for when out of order,
nested, array, or mixed initialization is used.

third_party/mesa/src/intel/vulkan/anv_magma_connection.cc contains usage
of field designators that are ordered differently from how they are
defined in their class. Until this is fixed upstream, we should disable
the warning for now.

This helps unblock the next clang roll.

BUG: 36018
Change-Id: Ie09925276718c915a729053e991a17d96591fdc6
1 file changed