native frameworks: 64-bit compile issues

- Fix format (print/scanf)
- Suppress unused argument warning messages (bonus)

Change-Id: I05c7724d2aba6da1e82a86000e11f3a8fef4e728
diff --git a/cmds/atrace/atrace.cpp b/cmds/atrace/atrace.cpp
index b500a6b..34dc9fe 100644
--- a/cmds/atrace/atrace.cpp
+++ b/cmds/atrace/atrace.cpp
@@ -17,6 +17,7 @@
 #include <errno.h>
 #include <fcntl.h>
 #include <getopt.h>
+#include <inttypes.h>
 #include <signal.h>
 #include <stdarg.h>
 #include <stdbool.h>
@@ -368,7 +369,7 @@
 static bool setTagsProperty(uint64_t tags)
 {
     char buf[64];
-    snprintf(buf, 64, "%#llx", tags);
+    snprintf(buf, 64, "%#" PRIx64, tags);
     if (property_set(k_traceTagsProperty, buf) < 0) {
         fprintf(stderr, "error setting trace tags system property\n");
         return false;
@@ -665,7 +666,7 @@
     close(traceFD);
 }
 
-static void handleSignal(int signo)
+static void handleSignal(int /*signo*/)
 {
     if (!g_nohup) {
         g_traceAborted = true;