Add glib-compile-resources test using g++
As per !287 (merged), the behaviour of C and C++ compilers differs in how they handle initialisation of sized arrays from string literals, and this caused a build failure in VTE with the glib-compile-resources
changes from 0d685b49.
Add a test which compiles a file generated by glib-compile-resources
using g++, to avoid regressions like that in future.