Add support for barriers in the compiler

The patch adds support for barriers in vertex, fragment and compute
shaders.

BUG:angleproject:1442
TEST:angle_unittests

Change-Id: Ic85c3337911851a93a3f56bd935774181600eddd
Reviewed-on: https://chromium-review.googlesource.com/380641
Commit-Queue: Olli Etuaho <oetuaho@nvidia.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
diff --git a/src/compiler/translator/SymbolTable.h b/src/compiler/translator/SymbolTable.h
index d0792c5..1fba212 100644
--- a/src/compiler/translator/SymbolTable.h
+++ b/src/compiler/translator/SymbolTable.h
@@ -405,6 +405,11 @@
         insertBuiltIn(level, op, "", rvalue, name, ptype1, ptype2, ptype3, ptype4, ptype5);
     }
 
+    void insertBuiltInFunctionNoParameters(ESymbolLevel level,
+                                           TOperator op,
+                                           const TType *rvalue,
+                                           const char *name);
+
     TSymbol *find(const TString &name,
                   int shaderVersion,
                   bool *builtIn   = NULL,