add FIXME note to test code

Author: Keenuts

clang/test/SemaHLSL/Semantics/position.ps.hlsl

@@ -1,5 +1,6 @@
 // RUN: %clang_cc1 -triple dxil-pc-shadermodel6.0-pixel -x hlsl -finclude-default-header -o - %s -ast-dump | FileCheck %s
 
+// FIXME(Keenuts): add mandatory output semantic once those are implemented.
 float4 main(float4 a : SV_Position2) {
 // CHECK: FunctionDecl 0x{{[0-9a-fA-F]+}} <{{.*}}> line:[[@LINE-1]]:8 main 'float4 (float4)'
 // CHECK-NEXT: ParmVarDecl 0x{{[0-9a-fA-F]+}} <{{.*}}> col:20 a 'float4':'vector<float, 4>'

clang/test/SemaHLSL/Semantics/position.ps.struct.hlsl

@@ -9,6 +9,7 @@ struct S {
 // CHECK:   HLSLSV_PositionAttr 0x{{[0-9a-fA-F]+}} <col:15> <<<NULL>>> 3 SemanticExplicitIndex
 };
 
+// FIXME(Keenuts): add mandatory output semantic once those are implemented.
 float4 main(S s) {
 // CHECK: FunctionDecl 0x{{[0-9a-fA-F]+}} <{{.*}}> line:[[@LINE-1]]:8 main 'float4 (S)'
 // CHECK-NEXT: ParmVarDecl 0x{{[0-9a-fA-F]+}} <{{.*}}> col:15 s 'S'