[build2] Issues with my first attempt at build2 CI

[Boris Kolpackov]

Klaim - Joël Lamotte <mjklaim at gmail.com> writes:

>     lib{gtest}: src/cxx{* -gtest-all -gtest_main}: include = false
> 
>     gtest\buildfile:111:58: error: expected newline instead of '='

I only get this error if I forget to checkout the gtest-origin
submodule ;-). I've also improved the diagnostics:

buildfile:111:15: error: no prerequisites in prerequisite-specific variable assignment