Fix warning in modf() precision test code

Bug: 22512069
Change-Id: I2a0ad0af5b9d4da3c55ca0925d375c4b5c3df307
diff --git a/modules/glshared/glsBuiltinPrecisionTests.cpp b/modules/glshared/glsBuiltinPrecisionTests.cpp
index 35590f4..bc7eb5d 100644
--- a/modules/glshared/glsBuiltinPrecisionTests.cpp
+++ b/modules/glshared/glsBuiltinPrecisionTests.cpp
@@ -3215,7 +3215,7 @@
 	}
 
 protected:
-	IRet	doApply				(const EvalContext& ctx, const IArgs& iargs) const
+	IRet	doApply				(const EvalContext&, const IArgs& iargs) const
 	{
 		Interval	fracIV;
 		Interval&	wholeIV		= const_cast<Interval&>(iargs.b);