repo: Update glslang known good

Change-Id: Ie35e275c84bc3e955a2cdc2eaafe9073e5fca044
diff --git a/scripts/known_good.json b/scripts/known_good.json
index 1708e8d..f74a591 100644
--- a/scripts/known_good.json
+++ b/scripts/known_good.json
@@ -6,7 +6,7 @@
       "sub_dir" : "glslang",
       "build_dir" : "glslang/build",
       "install_dir" : "glslang/build/install",
-      "commit" : "a8453d4bc00998049db0d448764784a6a0767539",
+      "commit" : "91ac4290bcf2cb930b4fb0981f09c00c0b6797e1",
       "prebuild" : [
         "python update_glslang_sources.py"
       ]