m4: Fix comparison bug in python macros
m4: Fix comparison bug in python macros

Reports say it fixes FreeBSD detection.

Tatsh/libimobiledevice,libimobiledevice/libimobiledevice,upbit/libimobiledevice,patweb/libimobiledevice,Tatsh/libimobiledevice,Tatsh/libimobiledevice,libimobiledevice/libimobiledevice,kalev/libimobiledevice,upbit/libimobiledevice,kalev/libimobiledevice,libimobiledevice-win32/libimobiledevice,libimobiledevice-win32/libimobiledevice,libimobiledevice-win32/libimobiledevice,libimobiledevice-win32/libimobiledevice,patweb/libimobiledevice,Tatsh/libimobiledevice,upbit/libimobiledevice,patweb/libimobiledevice,kalev/libimobiledevice