Do not test for C99 and GNU style variadic macros.

C++11 supports C99 variadic macros.
Do not check for GCC's __sync_*_and_fetch() built-ins.

We use C++11 atomics exclusively now.
Assume C++11 atomics and threads. Remove checks.
Update ThreadPool.
Add .rc file to include DLL version information on Windows
AUTHORS: Mention Oskari Timperi.
Move Win32-specific code under corresponding #ifdef
Remove unused typedef
patternlayout.cxx: Allow negative maximal length in pattern specifier to make
trimming of end instead of beginning possible. E.g., allow %.-1p to get initial
letters of log level.
Update to libtool 2.4.3.
win32.h: Fix unbalanced #if/#endif compilation error.
timehelper.h: Add cast to silence conversion warning.
socket.cxx: Work around for std::array<> initialization with MSVC issue.
TTCCLayout: Implement missing configuration features from log4j.
configurator.h: Use "true" instead of "enabled".
SyslogAppender: Recognize "SyslogHost" property in addition to "host".
Update to libtool 2.4.4.
msvc12/log4cplus.props: Raise default Windows version to 0x0600, i.e., Windows Vista.
src/socket.cxx: Avoid braced initializer to avoid #ifdef.
spi/rootlogger.h: Avoid symbol hiding warning with MSVC.