Use String8/16 c_str [binder]

Current String8::string() has two problems: it may suggest it's
returning a std::string and also prevents a drop-in replacement
with std::string.

Bug: 295394788
Test: make checkbuild
Change-Id: I1eb6ddebe3faede57f3e6f046da572a79056125a
diff --git a/libs/binder/ProcessState.cpp b/libs/binder/ProcessState.cpp
index 02b0447..8ec4af9 100644
--- a/libs/binder/ProcessState.cpp
+++ b/libs/binder/ProcessState.cpp
@@ -401,9 +401,9 @@
 {
     if (mThreadPoolStarted) {
         String8 name = makeBinderThreadName();
-        ALOGV("Spawning new pooled thread, name=%s\n", name.string());
+        ALOGV("Spawning new pooled thread, name=%s\n", name.c_str());
         sp<Thread> t = sp<PoolThread>::make(isMain);
-        t->run(name.string());
+        t->run(name.c_str());
         pthread_mutex_lock(&mThreadCountLock);
         mKernelStartedThreads++;
         pthread_mutex_unlock(&mThreadCountLock);
@@ -505,7 +505,7 @@
 }
 
 void ProcessState::giveThreadPoolName() {
-    androidSetThreadName( makeBinderThreadName().string() );
+    androidSetThreadName(makeBinderThreadName().c_str());
 }
 
 String8 ProcessState::getDriverName() {