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

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.