Add fuzzing stub for AddrMan deserialization

src/fuzzing/DeserializeAddrMan/fuzz.cpp

@@ -0,0 +1,13 @@
+#include "addrman.h"
+#include "streams.h"
+
+int main (int argc, char *argv[]) {
+    CAddrMan addrman;
+    CAutoFile filein(fopen(argv[1], "rb"), SER_DISK, CLIENT_VERSION);
+    try {
+        filein >> addrman;
+        return 0;
+    } catch (const std::exception&) {
+        return -1;
+    }
+}