patch 8.0.0466: still macros that should be all-caps

Problem:    There are still a few macros that should be all-caps.
Solution:   Make a few more macros all-caps.
diff --git a/src/gui_beval.c b/src/gui_beval.c
index c06e75a..818a50b 100644
--- a/src/gui_beval.c
+++ b/src/gui_beval.c
@@ -1054,7 +1054,7 @@
 #endif
 
 	/* Look up the RGB values of the SpecialKey foreground color. */
-	aep = syn_gui_attr2entry(hl_attr(HLF_8));
+	aep = syn_gui_attr2entry(HL_ATTR(HLF_8));
 	pixel = (aep != NULL) ? aep->ae_u.gui.fg_color : INVALCOLOR;
 	if (pixel != INVALCOLOR)
 # if GTK_CHECK_VERSION(3,0,0)