Enable fully static binaries of unbound and drill

[klutchell]

Resolves: #198
See: NLnetLabs/unbound#91

[klutchell]

This seems to increase the compressed image size from ~5MB to ~12MB so we should inspect the filesystem differences and consider if this is worthwhile.

These entries have been added to klutchell/unbound:main: None

These entries have been deleted from klutchell/unbound:main:
FILE                              SIZE
/lib                              5.2M
/lib/ld-musl-x86_64.so.1          602.6K
/lib/libcrypto.so.3               4.1M
/lib/libssl.so.3                  532.1K
/usr/lib                          864.6K
/usr/lib/libevent-2.1.so.7        294.3K
/usr/lib/libexpat.so.1            129.8K
/usr/lib/libgcc_s.so.1            117.8K
/usr/lib/libsodium.so.23          322.6K

These entries have been changed between klutchell/unbound:main and klutchell/unbound:build-kyle-fully-static:
FILE                               SIZE1          SIZE2
/usr/sbin/unbound                  1.2M           5.3M
/usr/sbin/unbound-anchor           1M             5.2M
/usr/sbin/unbound-host             1013.9K        5.1M
/usr/sbin/unbound-checkconf        941.4K         5M
/usr/bin/drill                     381.9K         3.7M
/usr/sbin/unbound-control          250.6K         4.3M