[adb data server] Initialize variable

servingComplete_ was left uninitialized and only set to 'true'
in the code.  We initialize it to the 'false' state to avoid
uninitialized references in SkipToRequest().

Bug: 150865433
Test: TreeHugger
Change-Id: Ia8a4d7135c432eb657543c5498fc9dbe8f4718b6
diff --git a/adb/client/incremental_server.cpp b/adb/client/incremental_server.cpp
index 1f47de8..737563c 100644
--- a/adb/client/incremental_server.cpp
+++ b/adb/client/incremental_server.cpp
@@ -228,7 +228,7 @@
     std::vector<char> pendingBlocks_;
 
     // True when client notifies that all the data has been received
-    bool servingComplete_;
+    bool servingComplete_ = false;
 };
 
 bool IncrementalServer::SkipToRequest(void* buffer, size_t* size, bool blocking) {