It used to support:
- a single string
- an array of anything
And as long as CustomTarget supported it too, everything worked fine.
So, a `files('foo')` worked but a `files('foo')[0]` did not, which is
silly... and it's not exactly terrible to use files() here, the input is
literally a list of source files.
Fixes building gnome-terminal
Fixes#9827
Test updated by Nirbheek Chauhan <nirbheek@centricular.com>
D lang compilers have an option -release (or similar) which turns off
asserts, contracts, and other runtime type checking. This patch wires
that up to the b_ndebug flag.
Fixes#7082