[vkgen] Don't queue types for fields with custom parsers

This ensures that unused parser blocks do not get emitted. In the
testing of the upcoming support for fixed arrays, the blend color
constants were being double emitted (both as custom and normal parser)
due to being an array. gcc did not like that (what with all those
warning flags).

libs/video/renderer/vulkan/vkgen/vkfieldcustom.r

@@ -65,4 +65,9 @@
 	return self;
 }
 
+-(int) searchType
+{
+	return 0;
+}
+
 @end

libs/video/renderer/vulkan/vkgen/vkfielddef.h

@@ -23,6 +23,7 @@
 -writeField;
 -writeSymbol;
 -(string) name;
+-(int) searchType;
 @end
 
 #endif//__renderer_vulkan_vkgen_vkfielddef_h

libs/video/renderer/vulkan/vkgen/vkfielddef.r

@@ -95,4 +95,9 @@
 	return field_name;
 }
 
+-(int) searchType
+{
+	return 1;
+}
+
 @end

libs/video/renderer/vulkan/vkgen/vkstruct.r

@@ -30,8 +30,19 @@
 -(void) queueFieldTypes
 {
 	qfot_struct_t *strct =&type.strct;
+	PLItem     *field_dict = [parse getObjectForKey:[self name]];
 
 	for (int i = 0; i < strct.num_fields; i++) {
+		qfot_var_t *var = &strct.fields[i];
+		if (field_dict) {
+			PLItem     *item = [field_dict getObjectForKey:var.name];
+			FieldDef   *def = [FieldDef fielddef:item
+										  struct:self
+										   field:var.name];
+			if (![def searchType]) {
+				continue;
+			}
+		}
 		Type       *type = [Type findType:var.type];
 		[type addToQueue];
 	}