SpirvShaderDebugger: Silence release only warning

Bug: b/148401179
Change-Id: I0f9458c8e7c8bb04b3b4443f30bb1b7f6c98d686
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/45354
Tested-by: Ben Clayton <bclayton@google.com>
Reviewed-by: Antonio Maiorano <amaiorano@google.com>
Kokoro-Result: kokoro <noreply+kokoro@google.com>
diff --git a/src/Pipeline/SpirvShaderDebugger.cpp b/src/Pipeline/SpirvShaderDebugger.cpp
index a456ef1..0f2fbbe 100644
--- a/src/Pipeline/SpirvShaderDebugger.cpp
+++ b/src/Pipeline/SpirvShaderDebugger.cpp
@@ -132,7 +132,9 @@
 	static constexpr auto KIND = Kind::Object;
 	inline Object(Kind kind)
 	    : kind(kind)
-	{}
+	{
+		(void)KIND;  // Used in debug builds. Avoid unused variable warnings in NDEBUG builds.
+	}
 	const Kind kind;
 
 	// kindof() returns true iff kind is of this type, or any type deriving from