fix check for non-positive array size

Test/baseResults/negativeArraySize.comp.out

+negativeArraySize.comp
+Warning, version 310 is not yet complete; most version-specific features are present, but some are missing.
+ERROR: 0:9: '' : array size must be a positive integer 
+ERROR: 1 compilation errors.  No code generated.
+
+
+Shader version: 310
+local_size = (1, 1, 1)
+ERROR: node is still EOpNull!
+0:7  Function Definition: main( (global void)
+0:7    Function Parameters: 
+0:?   Linker Objects
+
+
+Linked compute stage:
+
+
+Shader version: 310
+local_size = (1, 1, 1)
+ERROR: node is still EOpNull!
+0:7  Function Definition: main( (global void)
+0:7    Function Parameters: 
+0:?   Linker Objects
+

Test/negativeArraySize.comp

+#version 310 es
+
+#ifdef GL_ES
+precision mediump float;
+#endif
+
+void main()
+{
+   float f[-2]; // cannot declare arrays with negative size
+}

Test/testlist

@@ -128,4 +128,5 @@ varyingArrayIndirect.frag
 voidFunction.frag
 whileLoop.frag
 nonVulkan.frag
+negativeArraySize.comp
 spv.atomic.comp

glslang/MachineIndependent/ParseHelper.cpp

@@ -2869,13 +2869,14 @@ bool TParseContext::containsFieldWithBasicType(const TType& type, TBasicType bas
 void TParseContext::arraySizeCheck(const TSourceLoc& loc, TIntermTyped* expr, TArraySize& sizePair)
 {
     bool isConst = false;
-    sizePair.size = 1;
     sizePair.node = nullptr;
 
+    int size = 1;
+
     TIntermConstantUnion* constant = expr->getAsConstantUnion();
     if (constant) {
         // handle true (non-specialization) constant
-        sizePair.size = constant->getConstArray()[0].getIConst();
+        size = constant->getConstArray()[0].getIConst();
         isConst = true;
     } else {
         // see if it's a specialization constant instead
@@ -2884,16 +2885,18 @@ void TParseContext::arraySizeCheck(const TSourceLoc& loc, TIntermTyped* expr, TA
             sizePair.node = expr;
             TIntermSymbol* symbol = expr->getAsSymbolNode();
             if (symbol && symbol->getConstArray().size() > 0)
-                sizePair.size = symbol->getConstArray()[0].getIConst();
+                size = symbol->getConstArray()[0].getIConst();
         }
     }
 
+    sizePair.size = size;
+
     if (! isConst || (expr->getBasicType() != EbtInt && expr->getBasicType() != EbtUint)) {
         error(loc, "array size must be a constant integer expression", "", "");
         return;
     }
 
-    if (sizePair.size <= 0) {
+    if (size <= 0) {
         error(loc, "array size must be a positive integer", "", "");
         return;
     }