[NaCl SDK] Fix initialization of pthread_t in dlopen example

Initializing a pthread_t to NULL (or any value really)
is not valid.  This causes a compiler warning with the new
arm glibc toolchain so needs to be fixed because we
enable the new toolchain.

Turns out the pid_ member was not even needed so this
change removes it and adds a pthread_detach call which
allows for freeing on the thread's resources
(in the absence of pthread_join).

CQ_EXTRA_TRYBOTS=tryserver.chromium.linux:linux_nacl_sdk;tryserver.chromium.mac:mac_nacl_sdk
BUG=505885

Review URL: https://codereview.chromium.org/1243123002

Cr-Commit-Position: refs/heads/master@{#339720}

1 files changed, 9 insertions, 4 deletions

diff --git a/native_client_sdk/src/examples/tutorial/dlopen/dlopen.cc b/native_client_sdk/src/examples/tutorial/dlopen/dlopen.cc
index 81aa015..1c64314 100644
--- a/native_client_sdk/src/examples/tutorial/dlopen/dlopen.cc
+++ b/native_client_sdk/src/examples/tutorial/dlopen/dlopen.cc
@@ -41,8 +41,7 @@ class DlOpenInstance : public pp::Instance {
         eightball_so_(NULL),
         reverse_so_(NULL),
         eightball_(NULL),
-        reverse_(NULL),
-        tid_(NULL) {}
+        reverse_(NULL) {}
 
   virtual ~DlOpenInstance() {}
 
@@ -61,11 +60,18 @@ class DlOpenInstance : public pp::Instance {
     // server.
     mount("", "/http", "httpfs", 0, "");
 
+    pthread_t thread;
     logmsg("Spawning thread to cache .so files...");
-    if (pthread_create(&tid_, NULL, LoadLibrariesOnWorker, this)) {
+    int rtn = pthread_create(&thread, NULL, LoadLibrariesOnWorker, this);
+    if (rtn != 0) {
       logmsg("ERROR; pthread_create() failed.");
       return false;
     }
+    rtn = pthread_detach(thread);
+    if (rtn != 0) {
+      logmsg("ERROR; pthread_detach() failed.");
+      return false;
+    }
     return true;
   }
 
@@ -160,7 +166,6 @@ class DlOpenInstance : public pp::Instance {
   void* reverse_so_;
   TYPE_eightball eightball_;
   TYPE_reverse reverse_;
-  pthread_t tid_;
 };
 
 class DlOpenModule : public pp::Module {