In construct like

%ifarch someotherarch
%define foo bar
%endif

the %define is expanded (thus %foo defined) even though it shouldn't.

The fix is that if spec->readStack->reading is 0, we skip the definition.
This may be done on low level (in %define, %global, ... definitions) or
at higher level: we simply don't call expandMacros() in copyNextLine()
function.
I like the latter more, see the attached patch.