chiron: gps: Remove usage of std::shared_ptr<T>::unique()

It has been deprecated in c++17 and removed in c++20.
Fixes:
gps/utils/LocIpc.h:119:43: error: no member named 'unique' in
    'std::shared_ptr<int>'
  119 |         if (nullptr != mSocket && mSocket.unique()) {
      |                                   ~~~~~~~ ^
1 error generated.

Change-Id: I10b2be9d07ede68c4083e6a12f2bd5679f603402

gps/utils/LocIpc.h

@@ -116,7 +116,7 @@ class LocIpcSender {
     }
 
     inline ~LocIpcSender() {
-        if (nullptr != mSocket && mSocket.unique()) {
+        if (nullptr != mSocket && mSocket.use_count() == 1) {
             ::close(*mSocket);
         }
     }