[rdtk] mark all WINPR_ATTR_MALLOC also nodiscard

rdtk/include/rdtk/rdtk.h

@@ -44,6 +44,7 @@ extern "C"
 	RDTK_EXPORT void rdtk_engine_free(rdtkEngine* engine);
 
 	WINPR_ATTR_MALLOC(rdtk_engine_free, 1)
+	WINPR_ATTR_NODISCARD
 	RDTK_EXPORT rdtkEngine* rdtk_engine_new(void);
 
 	/* Surface */

rdtk/librdtk/rdtk_font.c

@@ -148,6 +148,7 @@ int rdtk_font_text_draw_size(rdtkFont* font, uint16_t* width, uint16_t* height,
 }
 
 WINPR_ATTR_MALLOC(free, 1)
+WINPR_ATTR_NODISCARD
 static char* rdtk_font_load_descriptor_file(const char* filename, size_t* pSize)
 {
 	WINPR_ASSERT(filename);