Roll external/re2/ 0c5616df9..5723bb895 (6 commits)
Roll external/re2/ 0c5616df9..5723bb895 (6 commits)

https://github.com/google/re2/compare/0c5616df9c0a...5723bb895031

$ git log 0c5616df9..5723bb895 --date=short --no-merges --format='%ad %ae %s'
2022-05-09 junyer Add GCC 12 to the build matrix.
2022-04-11 junyer Switch to `cxx_std_11` as per best current practice.
2022-04-08 junyer Mea culpa. The `DCHECK` needs to be an `if`.
2022-04-08 junyer Use `size_t` to stop MSVC griping about conversion.
2022-04-08 junyer `#include` `<cmath>` instead of `<math.h>`.
2022-04-06 junyer Prune `PrefilterTree` edges instead of nodes.

Created with:
  roll-dep external/re2

KhronosGroup/SPIRV-Tools,KhronosGroup/SPIRV-Tools,KhronosGroup/SPIRV-Tools,KhronosGroup/SPIRV-Tools,KhronosGroup/SPIRV-Tools,KhronosGroup/SPIRV-Tools,KhronosGroup/SPIRV-Tools,KhronosGroup/SPIRV-Tools