libsnapshot: Fix uninitialized variables

We fix two separate instances of classes not initializing members
in their constructors.

Test: TreeHugger
Change-Id: If1b7a7625572c9b005f9b8331b282ed11ceb6e97
diff --git a/fs_mgr/libsnapshot/make_cow_from_ab_ota.cpp b/fs_mgr/libsnapshot/make_cow_from_ab_ota.cpp
index 0b40fd6..d0b8f52 100644
--- a/fs_mgr/libsnapshot/make_cow_from_ab_ota.cpp
+++ b/fs_mgr/libsnapshot/make_cow_from_ab_ota.cpp
@@ -252,7 +252,7 @@
 
 class PuffInputStream final : public puffin::StreamInterface {
   public:
-    PuffInputStream(uint8_t* buffer, size_t length) : buffer_(buffer), length_(length) {}
+    PuffInputStream(uint8_t* buffer, size_t length) : buffer_(buffer), length_(length), pos_(0) {}
 
     bool GetSize(uint64_t* size) const override {
         *size = length_;
@@ -472,7 +472,7 @@
 class ExtentIter final {
   public:
     ExtentIter(const ContainerType& container)
-        : iter_(container.cbegin()), end_(container.cend()) {}
+        : iter_(container.cbegin()), end_(container.cend()), dst_index_(0) {}
 
     bool GetNext(uint64_t* block) {
         while (iter_ != end_) {