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/cygwin.din

@@ -485,8 +485,8 @@ jn
 _jn = jn
 jnf
 _jnf = jnf
-_kill
-kill = _kill
+kill
+_kill = kill
 labs
 _labs = labs
 lchown