install-only distributions probably don't need .a files

```
$ find . -name \*.a -exec du -ch {} +
148K ./lib/thread2.8.9/libthread2.8.9.a
492K ./lib/Tix8.4.3/libTix8.4.3.a
516K ./lib/itcl4.2.4/libitcl4.2.4.a
4.0K ./lib/itcl4.2.4/libitclstub4.2.4.a
1.2M total
```

I _think_ these are not particularly useful in the install-only distribution, and we could save some space. We skip shipping libpython.a but not these.

Start by locating how the install-only distribution is assembled and compare its handling of libpython.a with the archives under lib/thread2.8.9, lib/Tix8.4.3, and lib/itcl4.2.4. Verify that unnecessary .a files are omitted from the distribution without removing required files, and compare the resulting size with the current 1.2 MB total.

Written by the indexing model from the issue text.