MIPS: Enable HAVE_ARCH_TRACEHOOK.

This enables /proc/<pid>/syscall and the ptrace PTRACE_GETREGSET and
PTRACE_SETREGSET operations.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

diff --cc arch/mips/Kconfig
Simple merge

diff --cc arch/mips/include/asm/ptrace.h
Simple merge

diff --cc arch/mips/include/asm/syscall.h
Simple merge