glcpp: Add line locations to "Unterminated #if" error message.
diff --git a/glcpp/glcpp.h b/glcpp/glcpp.h
index 45bbff3..4a2489a 100644
--- a/glcpp/glcpp.h
+++ b/glcpp/glcpp.h
@@ -131,6 +131,7 @@
 
 typedef struct skip_node {
 	skip_type_t type;
+	YYLTYPE loc; /* location of the initial #if/#elif/... */
 	struct skip_node *next;
 } skip_node_t;