Roll third_party/shaderc/ f085b9745..f175adffa (4 commits)

https://chromium.googlesource.com/external/github.com/google/shaderc/+log/f085b9745fc1..f175adffa9d2

$ git log f085b9745..f175adffa --date=short --no-merges --format='%ad %ae %s'
2020-04-02 rharrison Add flag to control if we build with -Werror (#1032)
2020-03-31 rharrison Add knob to control force_zero_initialized_variables (#1028)
2020-03-31 dgkoch update glslang to SDK-Candidate-2 tag (#1027)
2020-03-30 rharrison Rolling 5 dependencies and updated exceptions (#1026)

Created with:
  roll-dep third_party/shaderc

Bug: dawn:347
Change-Id: Iacd580226c983ad8db71a3b6624ee89ae5c66931
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/18781
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Austin Eng <enga@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
diff --git a/DEPS b/DEPS
index f596feb..1565abd 100644
--- a/DEPS
+++ b/DEPS
@@ -69,7 +69,7 @@
     'condition': 'dawn_standalone',
   },
   'third_party/shaderc': {
-    'url': '{chromium_git}/external/github.com/google/shaderc@f085b9745fc1b8471f42aa2f8c54f3c73878ef07',
+    'url': '{chromium_git}/external/github.com/google/shaderc@f175adffa9d2da6ae18a5f8d54e7b5f27df0f1c2',
     'condition': 'dawn_standalone',
   },