GH-131296: fix clang-cl warning on Windows in pytime.c

[chris-eibl]

This line

cpython/Python/pytime.c

Line 918 in 0ce056d

PyTime_tns=large.QuadPart*100-11644473600000000000;

produces

..\Python\pytime.c(918,42): warning : integer literal is too large to be represented in a signed integer type, interpreting as unsigned [-Wimplicitly-unsigned-literal] 

Let's convert it to

PyTime_tns= (large.QuadPart-116444736000000000) *100;

which produces no warning but the exact same code: https://godbolt.org/z/r97Yadj5s

I think this is a skip news.

• Issue: clang-cl issues many warnings when building on Windows #131296