K 10
svn:author
V 3
kib
K 8
svn:date
V 27
2016-08-27T23:03:23.470470Z
K 7
svn:log
V 574
Do not obliterate errno value in the main thread during ptrace(2) call on x86.

Since ptrace(2) syscall can return -1 for non-error situations, libc
wrappers set errno to 0 before performing the syscall, as the service
to the caller.  On both i386 and amd64, the errno symbol was directly
referenced, which only works correctly in single-threaded process.

Change assembler wrappers for ptrace(2) to get current thread errno
location by calling __error().  Allow __error interposing, as
currently allowed in cerror().

Sponsored by:	The FreeBSD Foundation
MFC after:	1 week

END