patch 9.0.2048: python: uninitialized warning

patch 9.0.2048: python: uninitialized warning

Problem:  python: uninitialized warning
Solution: initialize 'minor' always

win32,py3: Fix uninitialized warning

Fix the following warning:
```
if_python3.c: In function 'py3_get_system_libname':
if_python3.c:879:16: warning: 'minor' may be used uninitialized [-Wmaybe-uninitialized]
  879 |             if (minor == PY_MINOR_VERSION)
      |                ^
if_python3.c:839:24: note: 'minor' was declared here
  839 |         long    major, minor;
      |                        ^~~~~
```

closes: #13368

Signed-off-by: Christian Brabandt <cb@256bit.org>
Co-authored-by: Ken Takata <kentkt@csc.jp>