Rename _kill() to kill() throughout. Rename _raise() to raise() throughout.

Rename _pid() to pid() throughout.
* Makefile.in: Compile some objects with -fomit-frame-pointer.
* cygwin.din: Reverse aliasing for _kill.
* syscalls.cc (_getpid_r): New function, implemented for newlib compatibility.
* shared.cc (open_shared): Remove reserving of memory since previous change
eliminate the need for this hack.

winsup/cygwin/thread.cc

@@ -2214,7 +2214,7 @@ __pthread_kill (pthread_t thread, int sig)
   if (thread->sigs)
     myself->setthread2signal (thread);
 
-  int rval = _kill (myself->pid, sig);
+  int rval = raise (sig);
 
   // unlock myself
   return rval;