[CMake] Temp workaround for FindPythonLibs on Win7 64-bit

[Jeremy Carter]

As a quick followup, this was an embarrasing mistake on my part.

CMake does read the correct registry. If the compiler it detects is
32-bit, it reads the 32-bit registry, if the compiler is 64-bit is
reads the 64-bit registry. I was intending to compile 64-bit, but had
two versions of MinGW on my system, and I hadn't noticed that CMake
was picking up the 32-bit MinGW, so it was correctly looking in the
32-bit registry, and correctly not finding 64-bit Python in there.

The patch in my original post is not necessary, as FindPythonLibs
works just fine. Sorry for the confusion.

Regards,
Jeremy Carter