opengl: Remove compiler warnings.

Simply remove multiple compiler warnings about unused parameter.
Note that this modifies three auto-generated files, which will
require fixing the 'emugen' program in the future.

Change-Id: I19edce7c6480770b893d033ed6b1c65744091d62
diff --git a/system/GLESv1_enc/gl_client_context.h b/system/GLESv1_enc/gl_client_context.h
index aa058ec..35fb27a 100644
--- a/system/GLESv1_enc/gl_client_context.h
+++ b/system/GLESv1_enc/gl_client_context.h
@@ -304,7 +304,7 @@
 	typedef gl_client_context_t *CONTEXT_ACCESSOR_TYPE(void);
 	static void setContextAccessor(CONTEXT_ACCESSOR_TYPE *f);
 	int initDispatchByName( void *(*getProc)(const char *name, void *userData), void *userData);
-	virtual void setError(unsigned int  error){};
+	virtual void setError(unsigned int  error){ (void)error; };
 	virtual unsigned int getError(){ return 0; };
 };