ada: Add Entry_Cancel_Parameter to E_Label
...and other (minor) changes.
gcc/ada/
* gen_il-gen-gen_entities.adb (E_Label): Add
Entry_Cancel_Parameter. This is necessary because
Analyze_Implicit_Label_Declaration set the Ekind to E_Label.
Without this change, this field would fail the vanishing-fields
check in Atree (which is currently commented out).
* einfo.ads (Entry_Cancel_Parameter): Document for E_Label.
* sem_eval.adb (Why_Not_Static): Protect against previous errors
(no need to explain why something is not static if it's already
illegal for other reasons).
* sem_util.ads (Enter_Name): Fix misleading comment.