Preventing Cygwin from picking up MinGW as host system

[Jan-Marek Glogowski]

Am 29.01.22 um 15:22 schrieb Ilmari Lauhakangas:
> So this beautiful annoyance came up during an email-driven 
> troubleshooting session:
> 
> checking build system type... x86_64-pc-cygwin
> checking host system type... x86_64-pc-mingw32
> 

[strip libassuan failure]

> Would be tempting to just uninstall MinGW, but the newcomer needs it for 
> other stuff. How can we teach Cygwin to ignore MinGW?

We can't and shouldn't. You simply must provide the correct 
--host=x86_64-pc-cygwin flag in this case.

But currently there is the other problem, that LO just forwards the 
build and host configure flags in case of cross-compiling. I'm not sure 
why this is implemented like this and it shouldn't be any problem to 
always forward this information to the external's configure… except for 
the Windows 32bit "cross-build" on Win64, where we're omitting the 
cross-toolset build, as it's not needed. Windows is already the slowest 
build, because it's currently not cached; PCH helps a bit.

So now there is https://gerrit.libreoffice.org/c/core/+/129153

It works here on Linux and maybe CI will work with it too. Then Cygwin + 
MingW setup should work with --host=x86_64-pc-cygwin.

HTH

Jan-Marek

P.S. and we should fail LO's configure, if the host is detected or given 
as *-mingw*, but that can be done in a separate patch.

P.P.S. this patch should be fine in any way, even by fixing the wrong 
host value by adapting Windows %PATH%.