MSYS2 build: header file missing

[Chris Johns]

> On 18 Dec 2020, at 5:54 pm, Sebastian Huber <sebastian.huber at embedded-brains.de> wrote:
> 
> Hello Robin,
> 
> my experience over the years with MSYS2 is that building GCC is always painful and a waste of time.

This is a bit harsh and I do not fully agree it is a waste of time. MSYS has proven to be an OK solution. Not perfect but It is the best I have experienced for native Windows gcc builds.

> What works quite reliably is building the RTEMS tools with a i686-w64-mingw32 cross-compiler on Linux. Most distributions include a standard package for this. 

The distro based builds have issues as well. You need to match the DLL runtimes used in the build on Windows or things get a bit weird. This adds a layer of complexity unless you know what you are doing.

> Since all parts of RTEMS build now with waf I think it is possible to build RTEMS applications on Windows without having to install MSYS2/MinGW. It should work with only a Python installation, but I haven't tested this yet.

This maybe true In theory but I have not been able to achieve it. 

Chris