Make the "switch-label not followed by statement" warning an error, depending on version.

Test/baseResults/spv.switch.frag.out

 spv.switch.frag
+Warning, version 310 is not yet complete; most version-specific features are present, but some are missing.
 WARNING: 0:121: 'switch' : last case/default label not followed by statements 
 WARNING: 0:134: 'switch' : last case/default label not followed by statements 
 WARNING: 0:139: 'switch' : last case/default label not followed by statements 
@@ -11,7 +12,7 @@ Linked fragment stage:
 // Generated by (magic number): 51a00bb
 // Id's are bound by 261
 
-                              Source ESSL 300
+                              Source ESSL 310
                1:             ExtInstImport  "GLSL.std.450"
                               MemoryModel Logical GLSL450
                               EntryPoint Fragment 4

Test/baseResults/switch.frag.out

 switch.frag
 ERROR: 0:11: 'switch' : condition must be a scalar integer expression 
 ERROR: 0:14: 'switch' : condition must be a scalar integer expression 
-WARNING: 0:21: 'switch' : last case/default label not followed by statements 
+ERROR: 0:21: 'switch' : last case/default label not followed by statements 
 ERROR: 0:28: 'switch' : cannot have statements before first case/default label 
 ERROR: 0:43: 'default' : duplicate label 
 ERROR: 0:63: 'case' : duplicated value 
@@ -15,10 +15,10 @@ ERROR: 0:115: 'default' : cannot be nested inside control flow
 ERROR: 0:119: 'case' : cannot appear outside switch statement 
 ERROR: 0:120: 'default' : cannot appear outside switch statement 
 ERROR: 0:126: 'onlyInSwitch' : undeclared identifier 
-WARNING: 0:128: 'switch' : last case/default label not followed by statements 
+ERROR: 0:128: 'switch' : last case/default label not followed by statements 
 ERROR: 0:140: 'nestedX' : undeclared identifier 
 ERROR: 0:157: 'nestedZ' : undeclared identifier 
-ERROR: 17 compilation errors.  No code generated.
+ERROR: 19 compilation errors.  No code generated.
 
 
 Shader version: 300

Test/spv.switch.frag

-#version 300 es
+#version 310 es
 precision mediump float;
 uniform int c, d;
 in float x;

glslang/MachineIndependent/ParseHelper.cpp

@@ -5186,8 +5186,16 @@ TIntermNode* TParseContext::addSwitch(TSourceLoc loc, TIntermTyped* expression,
     if (switchSequence->size() == 0)
         return expression;
 
-    if (lastStatements == 0)
-        warn(loc, "last case/default label not followed by statements", "switch", "");
+    if (lastStatements == 0) {
+        // This was originally an ERRROR, because early versions of the specification said
+        // "it is an error to have no statement between a label and the end of the switch statement."
+        // The specifications were updated to remove this (being ill-defined what a "statement" was),
+        // so, this became a warning.  However, 3.0 tests still check for the error.
+        if (profile == EEsProfile && version <= 300 && (messages & EShMsgRelaxedErrors) == 0)
+            error(loc, "last case/default label not followed by statements", "switch", "");
+        else
+            warn(loc, "last case/default label not followed by statements", "switch", "");
+    }
 
     TIntermAggregate* body = new TIntermAggregate(EOpSequence);
     body->getSequence() = *switchSequenceStack.back();