Add ES 3.1 compatibility to 4.5 and the atomic memory functions (e.g. atomicAdd).

git-svn-id: https://cvs.khronos.org/svn/repos/ogl/trunk/ecosystem/public/sdk/tools/glslang@27715 e7fa87d3-cd2b-0410-9028-fcbf551c1848

Test/310.comp

@@ -150,3 +150,14 @@ void opac()
     countArr[2];
     countArr[i];
 }
+
+shared int atomi;
+shared uint atomu;
+
+void atoms()
+{
+    int origi = atomicAdd(atomi, 3);
+    uint origu = atomicAnd(atomu, 7u);
+    origi = atomicExchange(atomi, 4);
+    origu = atomicCompSwap(atomu, 10u, 8u);
+}