Use String8/16 c_str (mainline modules)

Bug: 295394788
Test: make checkbuild
Change-Id: Ia266bccfc9100da25d8605d93c1298a341d2b11a
diff --git a/media/module/foundation/ALooperRoster.cpp b/media/module/foundation/ALooperRoster.cpp
index 4334f1e..451725d 100644
--- a/media/module/foundation/ALooperRoster.cpp
+++ b/media/module/foundation/ALooperRoster.cpp
@@ -168,7 +168,7 @@
         }
         s.append("\n");
     }
-    (void)write(fd, s.string(), s.size());
+    (void)write(fd, s.c_str(), s.size());
 }
 
 }  // namespace android