Roll SPIRV-Tools to d38a0a3

This pulls in:
 * d38a0a3 Validation within function body when doing a FunctionCall.
 * 6aa8a59 Simplify validation ProcessInstruction

TBR=dsinclair@chromium.org

Bug: 870156
Change-Id: Ia5fb99a01273b46602aaf49429a2ddc632d61531
Reviewed-on: https://chromium-review.googlesource.com/1161287Reviewed-by: dsinclair <dsinclair@chromium.org>
Commit-Queue: dsinclair <dsinclair@chromium.org>
Cr-Commit-Position: refs/heads/master@{#580362}

DEPS

@@ -213,7 +213,7 @@ vars = {
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling feed
   # and whatever else without interference from each other.
-  'spv_tools_revision': 'de9496e9f1b9d74c117fb4c4552ef0f5d74b8cbd',
+  'spv_tools_revision': 'd38a0a3b4476798744c4223acbefab3af97698fd',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling feed
   # and whatever else without interference from each other.