Removed check for posix version so that missing O_CLOEXEC leads to
compiler error.
Removed extra function since it hat no real purpose anymore.
Error behavior between Windows and Unix now equivalent.
Using the SPDLOG_PREVENT_CHILD_FD option there where still a race when
a other thread was using fork and exec in between the call to fopen and fcntl.
Using open and O_CLOEXEC when possible prevents this race.
I have no idea if this problem exists on Windows.
Ringbuffer sink keeps user-given number of most recent log messages in
memory and returns them upon request (using the ringbuffer_sink::last
method). This can be useful for e.g. remote debugging of a running app.
The meaning of using quotes to #include is implementation defined, so it
may or not may be what we want. At least POSIX
(https://pubs.opengroup.org/onlinepubs/9699919799/utilities/c99.html)
says: "headers whose names are enclosed in double-quotes ( "" ) shall be
searched for first in the directory of the file with the #include line",
so not what we want since "spdlog" ends up twice in the path.
`__cplusplus_winrt` only detected C++/CX (which can be used without compiling for UWP, SetHandleInformation would be available in those cases), and did not detect native UWP C++. This patch fixes that by using the WINAPI_FAMILY_PARTITION macro in the Windows SDK headers in the same way those headers remove SetHandleInformation in UWP builds.
