MFH: r449673

www/firefox: unbreak on powerpc64, sparc64

In file included from objdir/dist/include/mozilla/dom/EventTarget.h:12:0,

from dom/base/nsPIDOMWindow.h:15,
from objdir/dist/include/mozilla/DOMEventTargetHelper.h:13,
from dom/presentation/PresentationAvailability.h:10,
from dom/presentation/AvailabilityCollection.cpp:10,
from objdir/dom/presentation/Unified_cpp_dom_presentation0.cpp:2:

dom/base/nsWrapperCache.h:48:1: error: static assertion failed: Only support 32-bit and 64-bit
static_assert(sizeof(void*) == 4, "Only support 32-bit and 64-bit");
^

Reported by: Martin Husemann (via upstream bug)
Approved by: ports-secteam blanket