patch 8.1.2012: more functions can be used as methods

Problem:    More functions can be used as methods.
Solution:   Make terminal functions usable as a method.  Fix term_getattr().
diff --git a/src/terminal.c b/src/terminal.c
index 95347a1..6d9fb24 100644
--- a/src/terminal.c
+++ b/src/terminal.c
@@ -5055,6 +5055,8 @@
     if (name == NULL)
 	return;
 
+    if (attr > HL_ALL)
+	attr = syn_attr2attr(attr);
     for (i = 0; i < sizeof(attrs)/sizeof(attrs[0]); ++i)
 	if (STRCMP(name, attrs[i].name) == 0)
 	{