Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Use the size of struct fpreg rather than of the pointer to it when copying
the FPU state.

Reviewed by: marcel
Approved by: re (kib)
MFC after: 1 week

Cleanup for WARNS 3.

Include string.h for memcpy() and memcmp().

Add code to implement register structure converter.

Correct the mess I made by committing from the wrong tree. Most
notably, this restores some of the contents in thread_db.h as well
as David Xu's copyright notice. This also fixes the includes in
the MD libpthread files which Scott tried to provide a quick fix
for.

Pointy hat: marcel

Add rudimentary support and stubs for libthr and libc_r on alpha, amd64,
i386, ia64 and sparc64. Add stubs for alpha, amd64, ia64 and sparc64 for
libpthread.

Restructure the source files to avoid unnecessary use of subdirectories
that also force us to use non-portable compilation flags to deal with
the uncommon compilation requirements (building archive libraries for
linkage into a shared library).

The libpthread support has been copied from the original local and
cleaned-up to make them WARNS=2 clean.
that also force us to use non-portable compilation flags to deal with
the uncommon compilation requirements (building archive libraries for
linkage into a shared library).

The libpthread support has been copied from the original local and
cleaned-up to make them WARNS=2 clean.

Tested on: amd64, i386, ia64