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
g-ir-scanner --no-libtool needed some fixes similar to [1] for Cygwin, as
well. Now that is done, it's possible to make these tests run and pass on
Cygwin.
[1] https://bugzilla.gnome.org/show_bug.cgi?id=781525
Ignore warning 2282 about GCC pragmas since they are emitted in system
headers and are extremely spammy. They are emitted because ICC pretends
to be GCC via C macros but doesn't implement some pragmas.
https://bugzilla.gnome.org/show_bug.cgi?id=776562
Also, append to LD_LIBRARY_PATH because ICC uses that for some internal
libraries such as libintlc.so.