Merge pull request #2072 from wilzbach/deprecate-rwm-shared

Fix error due to deprecated rwm for shared variables
merged-on-behalf-of: Petar Kirov <ZombineDev@users.noreply.github.com>

Author: dlang-bot

src/core/sync/mutex.d

@@ -318,7 +318,7 @@ unittest
         void useResource() shared @safe nothrow @nogc
         {
             mtx.lock_nothrow();
-            cargo++;
+            *(cast()&cargo) += 1;
             mtx.unlock_nothrow();
         }
     }