[build2] Issue building empty library with b

[Boris Kolpackov]

Aaditya Kalsi <aadityakalsi at gmail.com> writes:

> I run vcvars64.bat before running b.
> 
> More verbose output:
> 
> link --version
> bin.ld @C:\Users\aadit\code\libakn-msvc\libakn\tests\
>   ld         link at C:\MinGW\msys\1.0\bin\link.exe
>   id         gnu
>   signature  link (GNU coreutils) 5.97

For some reason link.exe from MSYS is before MSVC's link.exe in your
PATH.

If I run the following in a session setup with vcvars64.bat:

> echo %PATH%
> where link.exe

I see link.exe found in the first directory listed in %PATH% (in my case
C:\Program Files (x86)\...\VC\Tools\MSVC\14.14.26329\bin\HostX64\x64).

In your case, however, C:\MinGW\msys\1.0\bin somehow ends up being
considered first, even though vcvars64.bat normally puts its paths
in the front. So there is something broken with your setup.