clean and full install of slackware64-current here
Code:
$ grep libpython3.6m.so.1.0 /var/log/packages/*
/var/log/packages/python3-3.6.3-x86_64-1:usr/lib64/libpython3.6m.so.1.0
$ ldd /usr/bin/gdb | grep libpython3.6m.so.1.0
libpython3.6m.so.1.0 => /usr/lib64/libpython3.6m.so.1.0 (0x00007f5878e09000)