[build2] build2 toolchain 0.5.0 released

[Boris Kolpackov]

Hi Max,

Moldmann Max (DC-MA/ENG52-NA) <Max.Moldmann at boschrexroth-us.com> writes:

> I ran some test with a 164 c-files project on my 3 year old laptop with 4 cores --> 8 virtual hyper threaded cores 
> Unfortunately the 0.5.0-a2 that you provided me a couple of weeks ago is a lot faster than the now released 0.5.0 
> (all tests on Windows 10, both versions were build using the same Mingw compiler).
> 
> Full rebuild of 164 c-files + 170 h-files
> 0.5.0-a2	20.5 seconds
> 0.5.0		36 seconds
> 
> Both versions reach 100% CPU load, but 0.5.0 not so consistently.

I think I know what the problem is. Can you perform a small experiment
for me:

1. In the upgrade configuration that you got after executing the build
   script, open libbutl-0.5.0\libbutl\process.cxx and change the line
   that reads:

   optional<bool> msys; // Absent if we don't know.

   To:

   optional<bool> msys (false); // Absent if we don't know.

2. Then change to build2-0.5.0\ (inside the same configuration) and run:

   > b install

   This should recompile process.obj, re-link b.exe, and install it.

3. Re-run your test to see what time you get.

Thanks,
Boris