I supported clang-cl with BUILD_SHARED_LIBS

Ubuntu 14.04 is about to be end-of-life and Bazel CI will stop supporting it shortly afterwards.

Context: https://groups.google.com/d/msg/bazel-dev/_D6XzfNkQQE/8TNKiNmsCAAJ

We need at least following defs to be set to print stacktrace in
failure signal handler.

- HAVE_UNWIND_H: on Linux and macOS. unwind.h is usually present
  by default on those OSes.
- HAVE_DLADDR: on macOS.

Windows is not cared because glog can not be built with bazel
on Windows today.

Release 0.4.0

 Protect macros from user code to the left of them

remove time from raw logging

for `&CheckStackAddress`, VisualStudio emits address of a trampoline like PLT, 
not the actual address of `CheckStackTrace`.

We need address of `CheckStackTrace` to guess the address range of the function.
`static` function seems to return the actual address of the function.

Fixes #421 

Stop using auto_ptr

std::unique_ptr requires -std=c++11. just use raw pointer.

project/google/glog -> project/google-admin/glog

windows/glog/logging.h is expected to be generated by
src/windows/preprocess.sh and should not be modified directly.

Use push/pop macro when supressing warning

* Same as PR #397 , but for the `.in` file. Useful for some unusual cross-platform build environments (e.g. WSL).

Support ABI tags after <local-source-name> in demangle.cc.
Update the reference URL.

Fixes #50 

* Fix demangling template parameter packs

Clang 4.0.1-10 and gcc 7.3.0 both mangle the function "void add<int>(int)" as
"_Z3addIJiEEvDpT_".  The template parameter pack is of the form
J <template-arg>* E

The opening character for a param pack could be either I or J, as libiberty
follows [1].  This change simply adds the J case.

[1] https://github.com/gcc-mirror/gcc/blob/fbd263526ad105a953fd51d9f7bca2c3f268cf82/libiberty/cp-demangle.c#L3209

build: cleanup temps and remove NEWS

The code references `@ac_cv_have_libgflags@` but not `@ac_cv_have_libgflags_h@`. This corrects that.

`int(with_gflags)` incorporates the possibility of `True/False`: https://github.com/bazelbuild/bazel/issues/4792

Fix unused variable warning in GCC

With automake GNU standard relaxed, these are no longer needed.

automake: relax GNU standard directory style

Now, we can build.

GNU standard assumes `README` under root dir, while PR #403
didn't fix the building issue exactually.
https://www.gnu.org/software/automake/manual/html_node/List-of-Automake-options.html

update README.md filename in Makefile.am

ci: add clang-cxx17 toolchain

remove register keyword from unittest