Linux: sys/ptrace.h -> nat/gdb_ptrace.h everywhere

So that we pick the enum __ptrace_request fix everywhere.

gdb/ChangeLog:
2015-07-24  Pedro Alves  <palves@redhat.com>

	* aarch64-linux-nat.c: Include nat/gdb_ptrace.h instead of
	sys/ptrace.h.
	* alpha-linux-nat.c: Likewise.
	* amd64-linux-nat.c: Likewise.
	* arm-linux-nat.c: Likewise.
	* hppa-linux-nat.c: Likewise.
	* i386-linux-nat.c: Likewise.
	* ia64-linux-nat.c: Likewise.
	* linux-fork.c: Likewise.
	* linux-nat.c: Likewise.
	* m32r-linux-nat.c: Likewise.
	* m68klinux-nat.c: Likewise.
	* mips-linux-nat.c: Likewise.
	* nat/linux-btrace.c: Likewise.
	* nat/linux-ptrace.c: Likewise.
	* nat/linux-ptrace.h
	* nat/mips-linux-watch.c: Likewise.
	* nat/x86-linux-dregs.c: Likewise.
	* ppc-linux-nat.c: Likewise.
	* s390-linux-nat.c: Likewise.
	* spu-linux-nat.c: Likewise.
	* tilegx-linux-nat.c: Likewise.
	* x86-linux-nat.c: Likewise.
	* xtensa-linux-nat.c: Likewise.

gdb/gdbserver/ChangeLog:
2015-07-24  Pedro Alves  <palves@redhat.c: Likewise.om>

	* linux-aarch64-low.c: Include nat/gdb_ptrace.h instead of
	sys/ptrace.h.
	* linux-arm-low.c: Likewise.
	* linux-cris-low.c: Likewise.
	* linux-crisv32-low.c: Likewise.
	* linux-low.c: Likewise.
	* linux-m68k-low.c: Likewise.
	* linux-mips-low.c: Likewise.
	* linux-nios2-low.c: Likewise.
	* linux-s390-low.c: Likewise.
	* linux-sparc-low.c: Likewise.
	* linux-tic6x-low.c: Likewise.
	* linux-tile-low.c: Likewise.
	* linux-x86-low.c: Likewise.

gdb/linux-fork.c

@@ -30,7 +30,7 @@
 #include "gdbthread.h"
 #include "source.h"
 
-#include <sys/ptrace.h>
+#include "nat/gdb_ptrace.h"
 #include "gdb_wait.h"
 #include <dirent.h>
 #include <ctype.h>