Use String8/16 c_str (mainline modules)

Bug: 295394788
Test: make checkbuild
Change-Id: Ia266bccfc9100da25d8605d93c1298a341d2b11a
diff --git a/media/module/libmediatranscoding/TranscodingClientManager.cpp b/media/module/libmediatranscoding/TranscodingClientManager.cpp
index 6dbcaf9..18702a4 100644
--- a/media/module/libmediatranscoding/TranscodingClientManager.cpp
+++ b/media/module/libmediatranscoding/TranscodingClientManager.cpp
@@ -354,7 +354,7 @@
         result.append(buffer);
     }
 
-    write(fd, result.string(), result.size());
+    write(fd, result.c_str(), result.size());
 }
 
 bool TranscodingClientManager::isTrustedCaller(pid_t pid, uid_t uid) {