Avoid C-style cast warnings

hardware/libhardware/include was being included with -isystem, which
hides warnings.  Use a macro to convert modules to hw_device_t** to call
the open function that works in C++ and C.

Bug: 32018017
Test: m -j
Change-Id: If68bf15581975f1217fcab366cef7bc784894641
diff --git a/include/hardware/gralloc.h b/include/hardware/gralloc.h
index ef86f90..65a7dc2 100644
--- a/include/hardware/gralloc.h
+++ b/include/hardware/gralloc.h
@@ -372,7 +372,7 @@
 static inline int gralloc_open(const struct hw_module_t* module, 
         struct alloc_device_t** device) {
     return module->methods->open(module, 
-            GRALLOC_HARDWARE_GPU0, (struct hw_device_t**)device);
+            GRALLOC_HARDWARE_GPU0, TO_HW_DEVICE_T_OPEN(device));
 }
 
 static inline int gralloc_close(struct alloc_device_t* device) {