Update SPIRV-Tools to stable. Also SPIRV-Headers to TOT. (#2250)

known_good.json

@@ -5,14 +5,14 @@
       "site" : "github",
       "subrepo" : "KhronosGroup/SPIRV-Tools",
       "subdir" : "External/spirv-tools",
-      "commit" : "4386ef4234e28f933412774b0ba718ae0e211333"
+      "commit" : "e128ab0d624ce7beb08eb9656bb260c597a46d0a"
     },
     {
       "name" : "spirv-tools/external/spirv-headers",
       "site" : "github",
       "subrepo" : "KhronosGroup/SPIRV-Headers",
       "subdir" : "External/spirv-tools/external/spirv-headers",
-      "commit" : "f8bf11a0253a32375c32cad92c841237b96696c0"
+      "commit" : "ac638f1815425403e946d0ab78bac71d2bdbf3be"
     }
   ]
 }