Remove obsolete forward about (extremely) old versions of Cython.

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with MSVC.

The current order results in compiler warnings on 32 bit machines, e.g.

src/llfuse.c: In function '__Pyx_PyInt_TrueDivideObjC':
src/llfuse.c:43980:17: warning: left shift count >= width of type
                 if (8 * sizeof(long) <= 53 || (__Pyx_sst_abs(size) <= 52 / PyLong_SHIFT) || likely(labs(a) <= (1L << 53))) {

Switching the order so that the left shift is closer to the sizeof test
avoids the warning, presumably because it makes it easier for the
compiler to see that the left shift is only executed on 64 bit.

Thanks to Christian Neukirchen for doing most of the work!

The current cast isn't doing anything, because the unary minus implicitly
upcasts to int again, resulting in warnings about potentially value altering
conversions on 32 bit systems.

Fixes issue #877.

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	Cython/Compiler/ExprNodes.py
	Cython/Shadow.py

speed up compilation for functions with large numbers of temps (already shows for a couple of thousand, e.g. for large list literals)