silence -Wparentheses-equality

silence -Wparentheses-equality

Clang has taken it upon itself to warn when an equality is wrapped in
double parentheses, e.g.

    ((foo == bar))

Which is a bit dumb, as any code along the lines of

    #define isBAR (foo == BAR)
    if (isBAR) {}

will trigger the warning.

This commit shuts clang up by putting in a harmless cast:

    #define isBAR cBOOL(foo == BAR)