Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

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

MFC r232263:

Define several extra macros in bsd.sys.mk and sys/conf/kern.pre.mk, to
get rid of testing explicitly for clang (using ${CC:T:Mclang}) in
individual Makefiles.

Instead, use the following extra macros, for use with clang:
- NO_WERROR.clang (disables -Werror)
- NO_WCAST_ALIGN.clang (disables -Wcast-align)
- NO_WFORMAT.clang (disables -Wformat and friends)
- CLANG_NO_IAS (disables integrated assembler)
- CLANG_OPT_SMALL (adds flags for extra small size optimizations)

As a side effect, this enables setting CC/CXX/CPP in src.conf instead of
make.conf! For clang, use the following:

CC=clang
CXX=clang++
CPP=clang-cpp

MFC r228578

In lib/libthread_db/arch/i386/libpthread_md.c, clang gives two incorrect
warnings about alignment, so turn -Wcast-align off for now.

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

MFtbemd:

Prefer MACHNE_CPUARCH to MACHINE_ARCH in most contexts where you want
to test of all the CPUs of a given family conform.

Build lib/ with WARNS=6 by default.

Similar to libexec/, do the same with lib/. Make WARNS=6 the norm and
lower it when needed.

I'm setting WARNS?=0 for secure/. It seems secure/ includes the
Makefile.inc provided by lib/. I'm not going to touch that directory.
Most of the code there is contributed anyway.

Cleanup for WARNS 6.

Cleanup for WARNS 3.

Cleanup for WARNS 2.

- Restore kse.h in this directory so other tools don't find it by mistake.
- Restore the ability to debug kse coredumps in 8.0.

Suggested by: marcel

- Remove libkse and related support code in libpthread from the build.
Don't remove the files yet. Kernel support will be removed shortly.

Bump library versions in preparation for 7.0.

Ok'd by: kan

Enable symbol versioning by default. Use WITHOUT_SYMVER to disable it.
Warning, after symbol versioning is enabled, going back is not easy
(use WITHOUT_SYMVER at your own risk).

Change the default thread library to libthr.

There most likely still needs to be a version bump for at least the
thread libraries. If necessary, this will happen later.

Remove libc_r support.

Add symbol versioning.

Reviewed by: davidxu

Bump the shared library version number of all libraries that have not
been bumped since RELENG_5.

Reviewed by: ru
Approved by: re (not needed for commit check but in principle...)

1. Use libpthread's exported symbols to calcuate offset in data structure
2. Enable TLS debugger support.

1.Use new way to check if a thread is in critical region, defer suspending
if it is true.
2.Add thread_db api td_thr_tls_get_addr to get tls address, the real code
is commented out util tls patch is committed.

Reviewed by: deischen

This library is not WARNS=2 clean for -O2 builds, because we include
headers from libpthread that are not WARNS=2 clean for -O2 builds.
Lower the WARNS level to 1. This is the highest level possible for
now.

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

Add my initial work of libthread_db. The library is used by gdb to debug
threaded process. Current, only libpthread is supported, but macrel will
work on it to support libthr and libc_r.