Use pthread_kill on solaris.

src/platform-solaris.cc

Index: src/platform-solaris.cc
diff --git a/src/platform-solaris.cc b/src/platform-solaris.cc
index 25efb0fa1ac80767b9e63b644efae45112d36329..794fe07cd6b4a9ca182bf7c2f1644984ea97b43e 100644
--- a/src/platform-solaris.cc
+++ b/src/platform-solaris.cc
@@ -673,11 +673,7 @@ class Sampler::PlatformData : public Malloced {
 
   void SendProfilingSignal() {
     if (!signal_handler_installed_) return;
-    // There doesn't seem to be a robust way to deliver a signal to a
-    // particular thread that may have terminated already. We send the
-    // signal to the whole process hoping the right thread will get
-    // it.
-    kill(vm_tgid_, SIGPROF);
+    pthread_kill(vm_tid_, SIGPROF);
   }
 
   void Sleep(SleepInterval full_or_half) {