- removed no longer used tthread.FSuspendedExternal

git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@28963 3ad0048d-3df7-0310-abae-a5850022a9f2
  * throw an error if RTLEventCreate() fails on Unix

git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@28964 3ad0048d-3df7-0310-abae-a5850022a9f2
  * replaced use of semaphores in Unix version of TThread for suspend/resume
    functionality with RTLEvent:
   o the thread manager semaphore functionality isn't used for anything else,
     and the main difference between mutex/condvar and semaphores is that the
     latter can be used for IPC (while the thread manager is always used
     within a single process) and that they are counting (but since a thread
     can only suspend itself nowadays, it cannot be suspended recursively)
   o OS X sandboxing does not support the use of semaphores (or rather: Apple
     does allow sandboxing rules that enable the use of IPC semaphores in the
     appstore)

git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@28965 3ad0048d-3df7-0310-abae-a5850022a9f2