dynamic-require: fast path for re-exported variables

When `dynamic-require` is used to access an export that isn't a
variable defined in the same module, `dynamic-require` falls
back to `eval` in a fresh namespace, which can be expensive.
The new fast path handles the case that a variable is re-exported.

The new fast path is relevant to deserialization, which now
uses a submodule that re-exports from an enclosing module.
increase timeout of `raco exe` test suite
fix closure type tracking for a procedure with only an unused rest arg

Closes PR 14259
compiler/zo-structs: fix docs to note 'fixnum and 'flonum types
raco: use executable yield handler before existing

Makes `raco` wait as it should for a GUI tool.

Closes PR 14261
raco setup: fix corners where db might not exist

Using something like `raco pkg remove` in an incompletely
set up installation could lead to failures attempting to
access a database file that isn't there.
add missing HISTORY entries based on my changes leading up to 6.0

Please merge to 6.0 (some of the history files already have
post-6.0 notes in them, but hopefully this patch still applies
cleanly)
fill in some missing history notes

Merge to v6.0
Update HISTORY

Please merge to v6.0
Add a HISTORY file for unstable

Note: I tried to reconstruct some history back
to 5.3.4, but it's not complete.

Please merge to v6.0
Correct pkgs urls, please include in v6
update HISTORY based on some of Jay's changes

please include in 6.0
Fix typo on pkg site
Remove secret information from pkg error messages
Fix PR14216
Use Racket navbar on pkgs. and have navbar link to pkgs.

Open question: Where does link to Planet go? Sam's new design has a natural place, but on the old site... it's not clear, community?
Adding suggestion about 1.0 package versions
Add history file for the profiler.
fix sqlite rollback-transaction in case of auto-rollback error

Merge to release branch.

An invalid (needs-rollback?) transaction may correspond to a closed
underlying transaction. In that case, don't issue ROLLBACK command.
fix problem with doc database in read-only mode

Now that the documentation-build phase of `raco setup` uses read-only
mode, contention between writing and reading sometimes (though
infrequently) triggers an SQLITE_IOERR_LOCK error. Change the SQLite
binding to expose that specific error, as well as SQLITE_IOERR_BLOCKED,
because a retry of the affected operation is appropriate.