linux/aarch64: sync sys/ptrace.h with Linux 4.15 [BZ #22433]

Remove compat-specific constants that were never exported by kernel
headers under these names.  Before linux commit v3.7-rc1~16^2~1 they
were exported with COMPAT_ prefix, and since that commit they are not
exported at all.

* sysdeps/unix/sysv/linux/aarch64/sys/ptrace.h (__ptrace_request):
Remove arm-specific PTRACE_GET_THREAD_AREA, PTRACE_GETHBPREGS,
and PTRACE_SETHBPREGS.

(cherry picked from commit 2fd4bbaa)