Tiny fix: initialize TickSample::frames_count with 0.

src/platform.h

Index: src/platform.h
diff --git a/src/platform.h b/src/platform.h
index f7fdafedd8ba8e4b64d986d55fcd6bf8d7be4c25..4522c7403142e303c6a931fff5d9be6c250b03e8 100644
--- a/src/platform.h
+++ b/src/platform.h
@@ -493,7 +493,7 @@ class Socket {
 // TickSample captures the information collected for each sample.
 class TickSample {
  public:
-  TickSample() : pc(0), sp(0), fp(0), state(OTHER) {}
+  TickSample() : pc(0), sp(0), fp(0), state(OTHER), frames_count(0) {}
   uintptr_t pc;  // Instruction pointer.
   uintptr_t sp;  // Stack pointer.
   uintptr_t fp;  // Frame pointer.