linux/powerpc: sync sys/ptrace.h with Linux 4.15 [BZ #22433, #22807]

linux/powerpc: sync sys/ptrace.h with Linux 4.15 [BZ #22433, #22807]

Tested with strace.

* sysdeps/unix/sysv/linux/powerpc/sys/ptrace.h (__ptrace_request): Add
PTRACE_GETREGS, PTRACE_SETREGS, PTRACE_GETFPREGS, PTRACE_SETFPREGS,
PTRACE_GETVRREGS, PTRACE_SETVRREGS, PTRACE_GETEVRREGS,
PTRACE_SETEVRREGS, PTRACE_GETREGS64, PTRACE_SETREGS64,
PTRACE_GET_DEBUGREG, PTRACE_SET_DEBUGREG, PTRACE_GETVSRREGS,
PTRACE_SETVSRREGS, and PTRACE_SINGLEBLOCK.

(cherry picked from commit f5f473a9d0e8fdbede858fa1ef0d01d12142367b)