Patch to fix kern_ptrace() on Alpha so it can be made mpsafe again.

[John Baldwin]

Can someone please test the patch at
http://www.FreeBSD.org/~jhb/patches/alpha.ptrace.patch and make sure that gdb 
and other utils that use ptrace still work ok?  If so, can you retry it with 
the ptrace() syscall marked MP safe (change STD in front of ptrace() in 
syscalls.master to MSTD and do a 'make init_sysent.c' in sys/kern) with 
WITNESS on and verify that it works ok?  Thanks.

-- 
John Baldwin <jhb at FreeBSD.org>  <><  http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve"  =  http://www.FreeBSD.org