add signal handler

src/rvprof_timing.c

@@ -0,0 +1,14 @@
+#include <time.h>
+#include <signal.h>
+#include <setjmp.h>
+#include "rvprof_internal.h"
+
+// global flag for cycle counter availability
+static volatile int g_cycle_counter_available = 0;
+static volatile jmp_buf g_cycle_test_jmpbuf;
+
+// signal handler for illegal instructions
+static void sigkill_handler(int sig){
+    g_cycle_counter_available = 0;
+    longjmp(g_cycle_test_jmpbuf, 1);
+}