Rename some Analysis and ResultsVisitor methods.

The words "before" and "after" have an obvious temporal meaning, e.g.
`seek_before_primary_effect`,
`visit_statement_{before,after}_primary_effect`. But "before" is also
used to name the effect that occurs before the primary effect of a
statement/terminator; this is `Effect::Before`. This leads to the
confusing possibility of talking about things happening "before/after
the before event".

This commit removes this awkward overloading of "before" by renaming
`Effect::Before` as `Effect::Early`. It also renames some of the
`Analysis` and `ResultsVisitor` methods to be more consistent.

Here are the before and after names:

- `Effect::{Before,Primary}`              -> `Effect::{Early,Primary}`
- `apply_before_statement_effect`         -> `apply_early_statement_effect`
- `apply_statement_effect`                -> `apply_primary_statement_effect`
- `visit_statement_before_primary_effect` -> `visit_after_early_statement_effect`
- `visit_statement_after_primary_effect`  -> `visit_after_primary_statement_effect`

(And s/statement/terminator/ for all the terminator events.)

compiler/rustc_borrowck/src/lib.rs

@@ -600,7 +600,7 @@ struct MirBorrowckCtxt<'a, 'infcx, 'tcx> {
 // 3. assignments do not affect things loaned out as immutable
 // 4. moves do not affect things loaned out in any way
 impl<'a, 'tcx> ResultsVisitor<'a, 'tcx, Borrowck<'a, 'tcx>> for MirBorrowckCtxt<'a, '_, 'tcx> {
-    fn visit_statement_before_primary_effect(
+    fn visit_after_early_statement_effect(
         &mut self,
         _results: &mut Results<'tcx, Borrowck<'a, 'tcx>>,
         state: &BorrowckDomain,
@@ -674,7 +674,7 @@ impl<'a, 'tcx> ResultsVisitor<'a, 'tcx, Borrowck<'a, 'tcx>> for MirBorrowckCtxt<
         }
     }
 
-    fn visit_terminator_before_primary_effect(
+    fn visit_after_early_terminator_effect(
         &mut self,
         _results: &mut Results<'tcx, Borrowck<'a, 'tcx>>,
         state: &BorrowckDomain,
@@ -787,7 +787,7 @@ impl<'a, 'tcx> ResultsVisitor<'a, 'tcx, Borrowck<'a, 'tcx>> for MirBorrowckCtxt<
         }
     }
 
-    fn visit_terminator_after_primary_effect(
+    fn visit_after_primary_terminator_effect(
         &mut self,
         _results: &mut Results<'tcx, Borrowck<'a, 'tcx>>,
         state: &BorrowckDomain,