One more attempt to fix FreeBSD

It seems sysctl.h is not self-contained, as I get missing symbols in the
header itself now. I am going to include all files that the file I moved
this from included, and hope that is enough.

llvm-svn: 298063

lldb/source/Plugins/Process/FreeBSD/FreeBSDThread.cpp

@@ -9,8 +9,12 @@
 
 // C Includes
 #include <errno.h>
+#include <pthread.h>
+#include <pthread_np.h>
+#include <stdlib.h>
 #include <sys/sysctl.h>
 #include <sys/types.h>
+#include <sys/user.h>
 
 // C++ Includes
 // Other libraries and framework includes