Andrew Noyes efc3045834 Disallow python2 for cmake scripts
The fdb c shim build requires python3. Let's not allow python2 to get
used there.

Otherwise we can see something like this:
```
FAILED: bindings/c/libfdb_c.so.init.c bindings/c/libfdb_c.so.tramp.S
cd /home/anoyes/workspace/foundationdb/build/bindings/c && /usr/bin/python2.7 /home/anoyes/workspace/foundationdb/contrib/Implib.so/implib-gen.py --target aarch64 --outdir /home/anoyes/workspace/foundationdb/build/bindings/c --dlopen-callback=fdb_shim_dlopen_callback /home/anoyes/workspace/foundationdb/build/lib/libfdb_c.so
  File "/home/anoyes/workspace/foundationdb/contrib/Implib.so/implib-gen.py", line 27
    sys.stderr.write(f'{me}: warning: {msg}\n')
```
2022-07-29 14:57:29 -07:00
..
2022-05-23 12:47:51 +02:00
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