Print what target is responsible for missing exe_wrapper error message

[sp1ritCS]

I'd be nice if the error message

meson/mesonbuild/backend/backends.py

Line 576 in f0851c9

msg = 'An exe_wrapper is needed but was not found. Please define one ' \

could contain the exe target responsible for triggering it.

At some point projects with significant complexity (esp. when you didn't write it / it got pulled in as a subproject) it isn't immediately obvious why the error occurred but printing the target might help some people (it did for me at least :))