Add required casts for clang/llvm -Wc++11-narrowing

system/core/include/utils/Mutex.h:134:25: error: non-constant-expression
cannot be narrowed from type 'long long' to '__kernel_time_t' (aka
'long') in initializer list [-Wc++11-narrowing]

system/core/include/utils/Mutex.h:135:26: error: non-constant-expression
cannot be narrowed from type 'long long' to 'long' in initializer list
[-Wc++11-narrowing]

Change-Id: Icb9df26aeb01617da5ab1c36987289f7c2b11954
diff --git a/include/utils/Mutex.h b/include/utils/Mutex.h
index 4fdd27f..a3b594d 100644
--- a/include/utils/Mutex.h
+++ b/include/utils/Mutex.h
@@ -131,8 +131,8 @@
 #if HAVE_ANDROID_OS
 inline status_t Mutex::timedLock(nsecs_t timeoutNs) {
     const struct timespec ts = {
-        /* .tv_sec = */ timeoutNs / 1000000000,
-        /* .tv_nsec = */ timeoutNs % 1000000000,
+        /* .tv_sec = */ static_cast<time_t>(timeoutNs / 1000000000),
+        /* .tv_nsec = */ static_cast<long>(timeoutNs % 1000000000),
     };
     return -pthread_mutex_timedlock(&mMutex, &ts);
 }