[libc] Fix global constructor being emitted for the RPC client

[jhuber6]

Summary

The indirection here is for some reason causing an unnecessary
constructor. If we leave this uninitialized we will get the default
constructor which simply zero initliaizes the global. I've checked the
output and confirmed that it uses the zeroinitializer so this should
be safe.

[jhuber6]

Better solution, default initializing everything else also prevents it from being emitted.

libc/src/__support/RPC/rpc.h

 template <bool Invert, typename Packet> struct Process {
   LIBC_INLINE Process() = default;
   LIBC_INLINE Process(const Process &) = delete;
   LIBC_INLINE Process &operator=(const Process &) = delete;
   LIBC_INLINE Process(Process &&) = default;
   LIBC_INLINE Process &operator=(Process &&) = default;
   LIBC_INLINE ~Process() = default;
 
-  uint64_t port_count;
-  cpp::Atomic<uint32_t> *inbox;
-  cpp::Atomic<uint32_t> *outbox;
-  Packet *packet;
+  uint64_t port_count = 0;
+  cpp::Atomic<uint32_t> *inbox = nullptr;
+  cpp::Atomic<uint32_t> *outbox = nullptr;
+  Packet *packet = nullptr;
 
   cpp::Atomic<uint32_t> lock[DEFAULT_PORT_COUNT] = {0};
 
   /// Initialize the communication channels.
   LIBC_INLINE void reset(uint64_t port_count, void *buffer) {
     this->port_count = port_count;
     this->inbox = reinterpret_cast<cpp::Atomic<uint32_t> *>(
         advance(buffer, inbox_offset(port_count)));