llvm: add URLs for HEAD version

Closes #30900.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>
Remove dead code

Formula objects are always constructed with an explicit name, so we no
longer need to special case an empty name or the name "__UNKNOWN__".
Add key? to BottleCollector
Mark private methods as private
Rename variable
Use [] on the instance rather than the wrapped hash
Update version of GAE SDK for Java to 1.9.7.

Update the url and sha1 checksum value.
app-engine-java-sdk: add 1.9.7 bottle.