[core] option to perform platform specific operations when creating/destroying core threads

platform/android/src/thread.cpp

@@ -1,5 +1,6 @@
 #include <mbgl/util/logging.hpp>
 #include <mbgl/util/platform.hpp>
+#include <mbgl/platform/thread.hpp>
 
 #include <sys/prctl.h>
 #include <sys/resource.h>
@@ -33,5 +34,11 @@ void makeThreadLowPriority() {
     setpriority(PRIO_PROCESS, 0, 19);
 }
 
+void attachThread() {
+}
+
+void detachThread() {
+}
+
 } // namespace platform
 } // namespace mbgl