python3.9: has_function not working for Visual Studio 2017 build

[joachimmetz]

Mainly informational

Tested with yara-python 4.0.4 and Python 3.9 on Windows 10 with Visual Studio 2017

Running: python.exe setup.py build fails with error: [WinError 1] Incorrect function

Unfortunately this appears to be a very generic error. Seeing the previous line reference memmem%RANDOM%.c this is likely related to the use of memmem. The same applies to strlcpy.

Removing memmem and strlcpy detection from setup.py

yara-python/setup.py

Line 224 in 924c816

if has_function('memmem'):

resolves the issue.

[joachimmetz]

This also applies to more functions it looks like has_function is not working for this build environment. I've removed with muted from has_function which allowed the module to build.