Use String8/16 c_str

Bug: 295394788
Test: make checkbuild
Change-Id: Ie50ae3befe3c858e5e13043b95c2f8d27619f151
diff --git a/rsDebugHelper.h b/rsDebugHelper.h
index 82aa314..5451084 100644
--- a/rsDebugHelper.h
+++ b/rsDebugHelper.h
@@ -38,7 +38,7 @@
 
     void dump() {
 #if !defined(RS_VENDOR_LIB) && !defined(RS_COMPATIBILITY_LIB)
-        ALOGV("%s", mStack.toString().string());
+        ALOGV("%s", mStack.toString().c_str());
         //mStack.dump();
 #endif
     }