tp: add missing array header

Change-Id: I46289d6ecc84c1a9d24496a89dd860c0b940922c
diff --git a/tools/gen_cc_proto_descriptor.py b/tools/gen_cc_proto_descriptor.py
index e9960f5..458fc5f 100755
--- a/tools/gen_cc_proto_descriptor.py
+++ b/tools/gen_cc_proto_descriptor.py
@@ -64,6 +64,7 @@
 
 #include <stddef.h>
 #include <stdint.h>
+#include <array>
 
 namespace perfetto {{