Add toolchain directory with cmake toolchain files used to find
compilers and set C++ versions

The following configurations are build on Windows using appveyor
service:
- enable MSVC 2015 SDK 8.1
- enable MSVC 2015
- enable MSVC 2017
- enable MSVC 2017 c++17
- enable mingw-cxx11
- enable mingw-gnuxx11
- enable mingw-cxx17

The following configurations are build on Linux using travis service:
- enable Ubuntu 14.04 amd64/i386, C++11
- enable Ubuntu 16.04 amd64/i386, C++11
- enable Ubuntu 18.04 amd64 C++98, C++11, GNU++11, C++17
- enable mingw-w64 on Ubuntu 18.04 amd64, C++11, GNU++11, C++17

The tests for cross compiled mingw windows binaries are run using wine64

Fix errors with BUILD_SHARED_LIBS=ON for Visual Studio 2017 (fixes #343)

resolves #338

fix glog.html link to gflags repository

Delete NEWS

remove unused 10 year old empty file

Fixes Issue https://github.com/google/glog/issues/325

Fix windows logging ut

tests: fix compilation with C++17

Remove throw() commands as they were deprecated with C++11 and are
removed with C++17

just like the null pointer test.

Fix mingw cross compile

This eliminates a conflict between glog and gflags preprocessor definition of GFLAGS_NAMESPACE that can cause the gflags namespace detection to fail (fixes #317).

- check in cmake if localtime_r exists
- if localtime_r is missing (MSVC, mingw-w64 on linux) redefine it using
  localtime_s

- fix dbhelp.h include
- fix dbghelp check and link

This was previously present in
https://github.com/bazelbuild/continuous-integration, but the Bazel team
asked us to move it to our repo. It will be helpful if we need to change
the build configuration, eg to add new platforms.

Resolve missing prototype warning

Fix redefined warnings from config.h

Make int conversion explicit and fix clang warning

The issue was caused by config.h header being included from both
header files and implementation files.

Proposed solution is to have regular header guard in the generated
config.h. Benefit of this solution is that it's least intrusive.
Downside is that it only solves issue for CMake build system, and
autoconf one is not fixed since header template is automatically
generated by autoheader who does not add header guard.

konsole family of terminfo supports colored output

Glog was missing colored output when running in terminal
who is set to konsole* TERM, even though the terminal
itself supports colored output.

Add extra terminfo to the check function, so now output
from Glog is properly colored.

* added dbghelp symbolizer support for mingw and cygwin
* fixed compiler errors in case <stdint.h> is not available
* cmake: check whether SymFromAddr actually works

CMake Update

- Use of Project version properties instead of custom variables
- fix missmatch between VERSION (build version) and SOVERSION (API version)
src: https://cmake.org/cmake/help/latest/prop_tgt/VERSION.html#prop_tgt:VERSION

CTest module already provides it

Useful when using glog as subproject.
Add an explanation at top like in gflags.git CMakeLists.txt