Users, who try to compile keep tripping over it, despite documentation
in the INSTALL file. Also, autoconf-archive might be hard to install
for users, who opted not to use MSYS2 and stick to MinGW only.
This commit bundles macros:
AX_CXX_COMPILE_STDCXX (version/serial 10)
AX_CXX_COMPILE_STDCXX_11 (version/serial 18)