[hlsl-out] avoid error X3694: race condition writing to shared resource detected

tests/in/spv/empty-global-name.spvasm

@@ -13,7 +13,7 @@
                         OpCapability Shader
                         OpMemoryModel Logical GLSL450
                         OpEntryPoint GLCompute %main "main" %global
-                        OpExecutionMode %main LocalSize 64 1 1
+                        OpExecutionMode %main LocalSize 1 1 1
 
                         OpName %global ""
                         OpDecorate %block Block

tests/out/hlsl/empty-global-name.hlsl

@@ -12,7 +12,7 @@ void function()
     return;
 }
 
-[numthreads(64, 1, 1)]
+[numthreads(1, 1, 1)]
 void main()
 {
     function();

tests/out/wgsl/empty-global-name.wgsl

@@ -11,7 +11,7 @@ fn function_() {
     return;
 }
 
-@compute @workgroup_size(64, 1, 1) 
+@compute @workgroup_size(1, 1, 1) 
 fn main() {
     function_();
 }