--- hw/xfree86/sdksyms.sh.orig	2015-04-04 17:38:46.756942409 +0300
+++ hw/xfree86/sdksyms.sh	2015-04-04 17:47:28.417349179 +0300
@@ -350,6 +350,23 @@
     if (sdk) {
 	n = 3;
 
+	# detect the following gcc5 cpp pattern and skip it:
+	# extern
+	# # 320 "../../include/os.h" 3 4
+	#     __attribute__((visibility("default")))
+	# # 320 "../../include/os.h"
+	# Note in this case the "extern " or "extern void " always has
+	# a trailing space
+	if ($0 ~ "^extern.* $") {
+	    getline;
+	    getline;
+	    getline;
+	    getline;
+	    n = 1;
+	    while ($n == " ")
+		n++;
+	}
+
 	# skip attribute, if any
 	while ($n ~ /^(__attribute__|__global)/ ||
 	    # skip modifiers, if any