Enforce "C" locale when building shaders in Dawn

All other backends do this (to avoid floating point numbers with
commas), was just missing here.

Needed for https://skia-review.googlesource.com/c/skia/+/368876

Change-Id: I506dbadf969c3b000b3e90b3f5864c4fe499a884
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/371873
Reviewed-by: John Stiles <johnstiles@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
1 file changed