Migrate INetd String16 method to std::string

Test: as follows
    - built
    - flashed
    - booted
    - system/netd/tests/runtests.sh passes
Change-Id: I7fe0e14a23b3c6f82dbfa17c7a44d221720976a0
diff --git a/server/FirewallController.cpp b/server/FirewallController.cpp
index dc4fa36..26c2126 100644
--- a/server/FirewallController.cpp
+++ b/server/FirewallController.cpp
@@ -308,8 +308,8 @@
 }
 
 int FirewallController::replaceUidChain(
-        const char *name, bool isWhitelist, const std::vector<int32_t>& uids) {
-   std::string commands4 = makeUidRules(V4, name, isWhitelist, uids);
-   std::string commands6 = makeUidRules(V6, name, isWhitelist, uids);
+        const std::string &name, bool isWhitelist, const std::vector<int32_t>& uids) {
+   std::string commands4 = makeUidRules(V4, name.c_str(), isWhitelist, uids);
+   std::string commands6 = makeUidRules(V6, name.c_str(), isWhitelist, uids);
    return execIptablesRestore(V4, commands4.c_str()) | execIptablesRestore(V6, commands6.c_str());
 }