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
Correct version_compare_condition_with_min() for the case where no minimum
version is established by the version constraint. Add a simple test.
Also fix test_feature_check_usage_subprojects by escaping regex
metacharacters.
if |condition| is '<', '<=' or '!=', the minimum version satisfying the
condition is 0, so the minimum version for a feature is never met.
if |condition| is '>=' or '==', the minimum version satisfying the condition
is the version compared with, so the minimum version for a feature must be
less than or equal to that.
if |condition| is '>', the minimum version satisfying the condition is
greater than the version compared with, so the minimum version for a feature
must be less than that
(it's this last condition that makes this function necessary, as in all
other cases we could establish a definite minimum version which we could
compare to see if it's less than or equal to the current version)