libsel4bench: Added missing #include <stdint.h>

sel4bench_private_arm1136 used uint32_t without including stdint.h

libsel4bench/arch_include/arm/sel4bench/arch/sel4bench_private_arm1136.h

diff --git a/libsel4bench/arch_include/arm/sel4bench/arch/sel4bench_private_arm1136.h b/libsel4bench/arch_include/arm/sel4bench/arch/sel4bench_private_arm1136.h
index 3753f20..1ee5601 100644
--- a/libsel4bench/arch_include/arm/sel4bench/arch/sel4bench_private_arm1136.h
+++ b/libsel4bench/arch_include/arm/sel4bench/arch/sel4bench_private_arm1136.h
@@ -11,6 +11,7 @@
 #ifndef __SEL4BENCH_PRIVATE_H__
 #define __SEL4BENCH_PRIVATE_H__
 
+#include <stdint.h>
 #include "sel4bench_events_arm1136.h"
 
 //function attributes